FORM 3 2013 PAPER 1 EAST ZONE CHEMISTRY

KCSE MOCKS

CHEMISTRY

FOR MARKING SCHEMES CALL/WHATSAPP

0705525657

(MOCK TRIALS 1-10)

A COMPILATION OF BIOLOGY MOCKS

IDEAL IN KCSE REVISION PURPOSES

MR ISABOKE 070552565

SET 2

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KCSE MOCK 1

233/1

CHEMISTRY

PAPER 1

(THEORY)

TIME: 2 HOURS

1. A mixture containing equal volumes of hydrogen and carbon (iv) oxide was introduced on one

end of a tube as shown .

Which gas would be detected at point C first Explain. (2 mks)

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2. The electron arrangement of ions X3+ and Y2- are 2.8 and 2.8.8 respectively.

(a) Write the electron arrangement of elements X and Y. (2 mks)

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(b) Write the formula of the compound that would be formed between X and Y. (1 mk)

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3. The curve below represents the variation of temperature with time when pure and impure

samples of solid were heated separately.

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Which curve shows the variation in temperature for the pure solid? Explain, (2 mks)

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4. In the redox reaction below

2H+ + Cr2O72- 9+ 3SO2 Cr3+ + 3SO2-

4 + H2O

Identify the reducing agent, explain your answer, (2 mks)

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5. Calculate the heat of formation of carbon (II) oxide from the following data (3 mks)

C(g) + O2(g) CO2(g) ∆H(c) = -394.8KJmole-1

CO(g) + ½O2(g) CO2(g) ∆H(c) = -285.6KJmole-1

6. State and explain using equations the changes in mass that occur when metallic copper and

copper (II) carbonate are separately heated in open crucibles. (3 mks)

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7. Study the flow chart below and answer the questions that follow.

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(a) Identify substance Y. (1 mk)

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(b) Identify process Z (1 mk)

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(c) State two uses of polyvinylchloride (1 mk)

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8. Nitrogen (iv) oxide can be prepared using the set up below.

(a) Write an equation for the reaction taking place in flask. (1 mk)

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(b) What property of the gas makes it possible to be collected using the method shown (1mk)

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9. The table blow gives the solubilities of potassium bromide and potassium sulphate at 00 C

and 400C.

Substance Solubility in g/100g water at

00C 400C

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Potassium bromide 55 75

Potassium sulphate 10 12

When an aqueous mixture containing 60g of potassium bromide and 7g of potassium sulphate in

100g of water art 800C was cooled to 00C, some crystals were formed. (1 mk)

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(i) Identify the crystals. (1 mks)

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(ii) Determine the mass of the crystals formed. (1 mk)

(iii) Name the method used to obtain the crystals. (1 mk)

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10. Complete the diagram below to show how alpha, beta and gamma emissions from a radio active

source can be distinguished from each other. Label your diagram. (3 mks)

11. 20cm3 of a solution containing 4g/l of sodium hydroxide was neutralized by 8cm3 of dilute

sulphuric acid. Calculate the concentration of sulphuric acid in moles per litre.

(Na=23, O=16, H=1) (3 mks)

12. (a) After use, a non-luminous flame should be put off or adjusted to luminous flame. Explain

why? (2 mks)

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(b) Explain how the hotness of a Bunsen burner can be increased. (1 mk)

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13. When steam was passed over heated charcoal as shown in the diagram below; hydrogen and

carbon (ii) dioxide were formed.

(a) Write the equation for the reaction which takes place. (1 mk)

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(b) Name two uses of carbon (ii) oxide gas which are also uses of hydrogen. (2 mks)

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14. Two solutions containing cations of metals P ad Q were separately added to a solution containing

chloride ions in both cases, a white precipitate was formed. It was divided into two portions. To

the first portion, a few drops of nitric acid was added. The chloride compound of P was warmed.

The chloride compound of Q dissolved while of P did not.

(a) Identify the ions of metal P and Q. (1 mk)

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(b) Write ionic equation for the reactions that occurred when cations of P and Q reacted with

chloride ions. (1 mk)

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15. (a) Name the raw materials from which sodium is extracted. (1 mk)

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(b) Give a reason why sodium is extracted using electrolysis. (1 mk)

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(c) Give two uses of sodium metal.. (1 mk)

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16. A polymer has the following structure

A sample of this polymer is found to have a molecules mass of 750, Determine the numbers of

monomers in the polymer (H=1, Cl=35.5, C=12) (2 mks)

The table below shows the PH values of solution I, II, III and IV.

Solution I II III IV

PH 2 7 11 14

17. (a) Which solution is likely to be calcium hydroxide. (1 mk)

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(b) Select two solution in which aluminium oxide is likely to dissolve. Give a reason.(2 mks)

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18. During the production of hydrogen Iodide, hydrogen reacts with iodine according to the

following equation.

Explain how the following would affect the yield of hydrogen Iodide.

(i) Increase in temp (1 mk)

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(ii) Increase in pressure (1 mk)

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19. Give two reasons why Helium is used in weather ballons. (2 mks)

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20. Below is a sketch of graph showing the change in viscosity (ease of flow) with temperature when

solid sulpher is heated.

Describe what happens to the supher molecules when sulpher is heated from 1500C to about

2000C. (3 mks)

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21. Both graphite and diamond are allotropes of carbon. Graphite conducts electricity while diamond

does not. Explain. (2 mks)

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22. The diagram below shows a student’s set up for the preparation and collection of hydrogen gas.

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(a) Write an equation for the production of hydrogen gas. (1 mk)

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(b) State and explain how the final volume of hydrogen gas produced would be affected if

80cm3 of 0.75m hydrochloric acid was used. (3 mks)

23. The drawings below illustrates a process

Describe the process. (3 mks)

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24. When a current of 0.82A was passed for 5 hours through a solution of metal Z, 2.65g of the

metal was deposited. Determine the charge on the ion of metal Z. (3 mks)

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25. Describe the process by which nitrogen is obtained from air on a large scale. (3 mks)

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26. The curves below were obtained when two equal volumes of hydrogen peroxide of the same

concentration were allowed to decompose separately. In one case, magnese (IV) oxide was

added to the hydrogen peroxide.

Which curve represents the decomposition of hydrogen peroxide with manganese (IV) oxide.

Explain. (3 mks)

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27. (a) Distinguish between endothermic and exothermic reaction. (1 mk)

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(b) Draw a well labeled diagram for an exothermic reaction. (2 mks)

28. A volume of 120cm3 of nitrogen gas diffused through a membrane in 40 seconds, how long will

240cm3 of carbon (IV) oxide diffuse through the same membrane. (3 mks)

29. (a) The table below contains atoms that form common radicals. Complete the table to show

radicals formed from various atoms. (2 mks)

Element N S

H NH+4

(b) What is a radical. (1 mk)

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KCSE MOCK 1

233/2

CHEMISTRY

PAPER 2

(THEORY)

TIME: 2 HOURS

1. In an experiment , apiece of magnesium was cleaned with steel wool. 2.4g of the cleaned

magnesium was placed in a crucible and completely burned in oxygen. After cooling the product

weighed 4.0g.

(a) Explain why it was necessary to clean the magnesium ribbon. (1 mks)

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(b) What observation was made in the crucible after burning. (1 mk)

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(c) Why was there an increase in mass? (1 mk)

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(d) Work out the empirical formula of the product (Mg=24.0, O=16.0) (3 mks)

(e) What was the aim of the experiment? (1 mk)

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(f) The product was shaken with dilute nitric acid and filtered.

(i) What type of reaction occurred (1 mk)

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(ii) Write an equation for he reaction. (1 mk)

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2. The flow chart below shows part of the process involved in large scale manufacturing of

sulphuric (VI) acid. Use it to answer the questions that follow.

(a) Identify two conditions required for a high yield of sulphur (VI) oxide in the reaction

chamber (2 mks)

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(b) Name substance R. (1 mk)

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(c) Write an equation for the reaction occurring in the absorption chamber (2 mks)

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(d) Give one pollination affect of the process (1 mk)

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(e) Complete the table below to show the observation made when concentrated sulphuric

(VI) acid is added to the substances shown. (2 mks)

Substance Observation

Iron fillings

Sugar crystals

(d) Zinc reacts with both concentrated and dilute sulphuric (VI) acid. Explain (2 mks)

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(g) Sulphuric acid contains sulphate ions. Explain how these ions are confirmed.(2 mks)

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(h) Give one use of sulphuric acid. (1 mk)

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3. (a) Identify the chief ore of iron. (1 mk)

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(b) The extraction of iron takes place in a blast furnace as shown below.

(i) Other than the iron are name other two raw materials put in the furnace.(2 mks)

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(ii) Describe the process which leads to the formation of iron in the blast furnace.

(3 mks)

(iii) State the purpose of limestone in the blast furnace. (1 mks)

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(iv) Give a reason why the melting point of the iron obtained from the blast furnace is

12000C while that of pure iron is 15330C (2 mks)

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(v) Give one gas which is recycled (1 mk)

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(vi) State one physical property of mother slag that allows it to be separated from

mother iron as shown in the figure. (1 mk)

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(vii) State one use of steel (1 mk)

4. The diagram below is part of a set up used to prepare and collect dry chlorine gas.

(i) Complete the diagram to show how a dry sample of chlorine gas can be collected(3 mks)

(ii) Write an equation for the reaction forming chlorine. (1 mks)

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(iii) Other than the manufacturing of weed killers name two (2) uses of chlorine.(2 mks)

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(v) 0.8g of aluminum reacted completely with chlorine gas. Calculate the volume of chlorine

gas used. (Molar gas volume is 24dm3, Al=27.0) (3 mks)

5. (a) The scheme below shows some of the reaction of solution Q. Study it and answer the

question that follows.

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(i) Give possible identity of substance M and Z (2 mks)

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(ii) Identity the anion in solution Q (1 mk)

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(iii) What type of reaction occurs at step I and II (2 mks)

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(iv) Write an equation for the reaction occurring at step IV (1 mk)

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(v) Explain how a sample of substance D can be obtained from the salt solution D.(2 mks)

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(vi) What difference in the observation would be made if sodium chloride solution is used

instead of barium chloride at step II. (2 mks)

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(b) Describe how a sample of iron chloride can be prepared by direct synthesis.(3 mks)

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6. (a) Below is a radio active decay series starting from;

(i) Identify the particles emitted in steps I and III (2 mks)

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(ii) Write the nuclear equation for the reaction which occurred in step V. (1 mk)

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(b) The table below gives the percentage of a radioactive isotope o Bismuth that remain after

decaying at different times.

(i) Plot a graph of the percentage of Bismuth remaining (vertical axis) against time .

(4 mks)

Time (min) 0 6 12 22 38 62 100

Percentage of Bismuth 100 81 65 45 29 12 3

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(ii) Using the graph, determine the;

I. Half life of the Bismuth isotope (1 mk)

II. Original mass of the Bismuth isotope given that the mass remained after

70 minutes was 0.16g. (2 mks)

(e) Explain why it is not safe to dissolve radioactive substances in containers made of

aluminum sheets. (2 mks)

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(d) Distinguish between nuclear fission and nuclear fusion. (1 mk)

7. Determine the molar enthalpy of combustion of ethanol, (density of water =1g/cm3, specific heat

capacity of water=4.2J/Kg/K, C=12.0, O=16.0, H=1.0) (9 mks)

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KCSE MOCK 2

CHEMISTRY

PAPER 1

THEORY

1. Identify and state the use of the apparatus represented below. (2 marks)

Name……………………………………………………………………

Use………………………………………………………………………

2. Give the systematic name of each of the compounds represented by the formulae below.

(3 marks)

(a) CH3C≡CCH3

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(b) CH3CH=CHCH2CH3

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3. A fixed mass of a gas occupies 105cm3 at -14 oC and 650mmHg. At what temperature will it have a

volume of 15cm3 if pressure is adjusted to 690mmHg? (3marks)

4. a) Using dots (.) and crosses (x) to represent electrons, show the bonding in the compounds formed

between magnesium and fluorine. (Atomic numbers; Mg= 12, F=9) (1 mark)

b) State one likely physical property of the compound formed between magnesium and

fluorine in (a) above. (1 mark)

5. A set-up to investigate electrical conductivity of substances was assembled as shown below.

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The bulb did not light.

(a) What was missing in the set-up? (1 mark)

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(b) The bulb lit when the omission was corrected. Explain. (2 marks)

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6. An oxide of copper in a porcelain boat was reduced by a stream of hydrogen. The results obtained

were as follows;

Mass of porcelain boat = 4.5g

Mass of boat + Oxide = 6.40g

Mass of boat + Copper = 6.02 g

i) Determine the empirical formula of the oxide. (3 marks)

ii) If the relative formula mass of the oxide is 80, determine its chemical formula.

(Cu = 64, O = 16) (1 mark)

7. Starting with copper metal, describe how to prepare solid copper (II) carbonate. (3 marks)

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8. The diagram below shows a ‘jiko’ when in use. Study it and answer the questions that follow

Region B

Region A

Burning charcoal

Air

Ash

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(a) Identify the gas formed at region B (1mk)

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(b) State and explain the observation made at region B (2mks)

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9. A student set up the following experiment to study the effect of heat on lead (II) nitrate.

i)Identify liquid X (1 mark)

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ii)Describe the test for gas Y. (1 mark)

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iii)Write a balanced chemical equation for the reaction. (1 mark)

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10. The set-up represented below can be used to separate ethanol from its mixture with water.

(a) Identify an error in the set-up. (1 mark)

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(b) Name this method of separation. (1 mark)

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(c) What properties make it possible to separate ethanol from water by this method? (1 mark)

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11. Describe how to distinguish between substances I and II .

(3 marks)

I.CH3CH3 II. HCCCH3

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12. Element K has two isotopes 20K and 22K with relative abundance of 90% and 10% respectively.

a) What are isotopes? (1 mark)

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b) Determine the relative atomic mass of element K. (2 marks)

13. Give one application of calcium oxide. (1 mark)

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…………………………………………………………………………………… 14. Consider the diagram below.

Name the regions labeled a, b, c. (3 marks)

a ……………………………………………………………………….

b ……………………………………………………………………….

c ……………………………………………………………………….

15. State one use of:

a) Calcium nitrate (1 mark)

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a

b

c

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b) Magnesium hydroxide (1 mark)

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16.. Some moist iron wool was placed in a test tube and the tube was inverted and set up as shown below.

The apparatus was left for one week. The water level rose and iron wool turned red-brown.

(i) Write the chemical equation to show the rusting of iron. (1 mark)

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(ii) Write the expression for an approximate percentage. (1 mark)

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(iii) State two similarities between rusting and combustion.

(a)

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(b)

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17. Sulphur burns in air to form a gaseous product.

i) What is the colour of the flame of burning sulphur? (1 mark)

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ii) Give an equation for the reaction that takes place when the gaseous product is bubbled through

water. (1 mark)

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x cm y cm

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iii)State one importance of the product formed in 17(ii) above. (1 mark)

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18. The PH values of some solutions labeled E to I are given in the table below. Use the information

to answer the questions that follow.

PH 14.0 1.0 8.0 6.5 7.0

Solution E F G H I

(a) Identify the solution with the highest concentration of hydroxide ions. Give a reason for

your answer. (2 marks)

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(b) Which solution can be used as a remedy for acid indigestion in the stomach?(1 mark)

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19. Four metals are labeled P, Q, R and S (not actual symbols). Metal P displaces metal S from its oxide

but cannot displace R from its oxide. Q when mixed with the oxide of R and heated, a reaction occurs.

Arrange the metals in order of reactivity, starting with the most reactive. (2 marks)

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20. A certain element Y has atomic number 15 and mass number of 31.

(a) Calculate the number of neutrons in the element. (1mk)

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(b) Write the electron arrangement of the ion formed by element Y. (1mk)

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(c) How would the atomic size of the above element compare with another atom X whose

atomic number is 11 and mass number 23? Explain. (1mk)

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21. The table below shows the first ionisation energies of elements P and Q. Element 1st Ionisation energy kJ/mole

P

Q

494

418

a)What do these values suggest about the reactivity of P compared to that of Q? Explain.

(2 marks)

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a) State two factors that influence ionization energy. (1 mark)

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22. Steam is passed over heated iron filings in a combustion tube.

(a) Name the products of this reaction. (2 mark)

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(b) Write an equation for the reaction that occurs. (1 mark)

1. ………………………………………………………………………………………………………

Diamond and graphite are allotropes of carbon.

(i) What are allotropes? (1mk)

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of structure and bonding explain why diamond is used in drilling through hard rocks while

graphite is a lubricant (2mks)

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24. 30cm3 of 0.5M hydrochloric acid was used to neutralize 25cm3 of sodium hydroxide solution.

Determine the concentration of sodium hydroxide in grams per litre. (3 marks)

(H=1, O=16, Na= 23)

25. The table below gives some information about the physical properties of four substances which

are represented by letters. L M N and K.

Substance Melting point Heat of

vaporization

Electrical Conductivity

Solid molten

L

M

High

High

High

High

Poor

Good

Poor

Good

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N

K

High

Low

High

Low

Poor

Poor

Good

Poor

Select with reasons an element which is likely to be:

(i) Copper metal (1mk)

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……………………………………………………………………………………………Silicon

(iv) oxide (1mk)

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m iodide (1mk)

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26. a) Write balanced chemical equations for reactions between chlorine and; (2 marks)

i) Concentrated sodium hydroxide

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ii) Dilute sodium hydroxide.

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b) State one observation made when a gas jar of moist hydrogen sulphide is inverted over a gas jar of

dry chlorine gas. (1 mark)

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27.a) Hydrogen sulphide gas is bubbled through bromine water.

i) Give two observations made. (1 mark)

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ii) Write an equation for the reaction that takes place. (1 mark)

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b) State the test for hydrogen sulphide gas. (1 mark)

……………………………………………………………………………………………………

……………………………………………………………………………………………………

28.(a) State Gay-Lussac’s law. (1 mark)

……………………………………………………………………………………………………

……………………………………………………………………………………………………

b) When 100cm3 of a gaseous hydrocarbon (CxHy) burns in 300cm3 of oxygen, 200cm3 of

carbon(IV)oxide and 200 cm3 of steam are formed.

Deduce the formula of the hydrocarbon. (2 marks)

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KCSE MOCK 2

233/2

CHEMISTRY PAPER 2

(THEORY)

TIME: 2 HOURS.

1. 5 grammes of potassium chlorate were added to two boiling tubes A and B, 2 grammesof Copper (II)

Oxide was then added to B and then both tubes were heated from the same sandbath as shown

below.

Glowing splints were lowered into the tubes, concurrently. During the heating, the splint in tube B

relight earlier than tube A.

A B

5g of KClO3 + 2g of CuO

5g of KClO3 Sandbath

Heat

(a) Explain why the glowing splint in B relights earlier than earlier A. (2 marks)

…………………………………………………………………………………………………………

….....

…………………………………………………………………………………………………………

….....

(b) The set up below was used to investigate a certain aspect about air.

Air

Burning

candle Dilute Sodium Hydroxide

(i) Draw a diagram to illustrate how it would look like at the end of the experiment. (2marks)

…………………………………………………………………………………………………………

….....

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….....

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…………………………………………………………………………………………………………

…….

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….....

(iii) Name two gases remaining at the end of the experiment. (2marks)

…………………………………………………………………………………………………………

…….

…………………………………………………………………………………………………………

….....

(iv) State why dilute Sodium Hydroxide solution was used in the experiment. (1mark)

…………………………………………………………………………………………………………

…….

…………………………………………………………………………………………………………

….....

(c) The diagram below shows how acidic and basic oxides fit into the general family of oxides.

(i) State the name given to the type of oxides that would be placed in the shaded area. (1 mark)

…………………………………………………………………………………………………………

…….

(ii) Write the formula of the two such oxides. (1mark)

…………………………………………………………………………………………………………

……

2. (a) Two reagents that can be used to prepare chlorine gas are Potassium – Manganate (VII) and

concentrated Hydrochloric acid.

(i) Write an equation for the reaction. (1mark)

…………………………………………………………………………………………………………

….....

…………………………………………………………………………………………………………

….....

(ii) Give the formula of another reagent that can be reacted with concentrated hydrochloric acid to

producechlorine gas. (1mar

…………………………………………………………………………………………………………

….....

Acidic

Oxides Basic

Oxides

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…………………………………………………………………………………………………………

….....

(iii) Describe how chlorine gas could be dried in the laboratory. (2marks)

…………………………………………………………………………………………………………

….....

…………………………………………………………………………………………………………

….....

(b) In an experiment, dry chlorine gas was reacted with aluminium as shown below.

(i) Name substance A (1mark)

…………………………………………………………………………………………………………

….....

(ii) Write an equation for the reaction that took place in the combustion tube.

…………………………………………………………………………………………………………

….....

…………………………………………………………………………………………………………

….....

(iii) When 0.84g of aluminium reacted completely with chlorine gas. Calculate the volume of

chlorine gas

used. Molar gas volume is 24dm3, Al = 27.0 (3marks)

…………………………………………………………………………………………………………

….....

…………………………………………………………………………………………………………

….....

…………………………………………………………………………………………………………

….....

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…………………………………………………………………………………………………………

….....

(iv) Give a reason why calcium oxide is used in the setup (1mark)

…………………………………………………………………………………………………………

….....

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….....

…………………………………………………………………………………………………………

….....

…………………………………………………………………………………………………………

….....

3. The grid below represents part of the periodic table. Study it and answer the questions that follow.

The

letters do not represent the actual symbols of the elements.

A K

B D I

F H L

C E J

(a) (i) Which letter represents a non metal that is least reactive? ( 1mark)

………………………………………………………………………………………………………

………………………………………………………………………………………………………

……

(ii) Why are elements D and E referred to as alkali earth metals? (1mark)

…………………………………………………………………………………………………………

….....

…………………………………………………………………………………………………………

….....

(b) How does the atomic radius of F and H compare? ( 2 marks)

………………………………………………………………………………………………………

………………………………………………………………………………………………………

……

(c) Select two letters representing a pair of elements that would react most explosively.( 1mark)

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………………………………………………………………………………………………………

………………………………………………………………………………………………………

……

(d) Write an equation showing how D forms its ions. (1 mark)

………………………………………………………………………………………………………

………………………………………………………………………………………………………

……

(e) Write the formulae of

(i) Bromide of D ( ½mark)

…………………………………………………………………………………………………………

….....

…………………………………………………………………………………………………………

….....

(ii) Sulphate of C ( ½mark)

…………………………………………………………………………………………………………

….....

…………………………………………………………………………………………………………

….....

(f) What type of bonding exists between.

(i) E and I ( ½mark)

…………………………………………………………………………………………………………

….....

…………………………………………………………………………………………………………

….....

(ii) G and I ( ½mark)

…………………………………………………………………………………………………………

….....

…………………………………………………………………………………………………………

….....

(g) Explain why the melting point of J is higher than that of I ( 2 marks

………………………………………………………………………………………………………

………………………………………………………………………………………………………

……

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4. (a) The diagram below was set up to study the products formed when a candle is burnt.

(i) State what would be observed in test tube B (1mark)

…………………………………………………………………………………………………………

….....

…………………………………………………………………………………………………………

….....

(ii) State and explain what would be observed if the suction pump is switched off. (2marks)

…………………………………………………………………………………………………………

….....

…………………………………………………………………………………………………………

….....

(iii) Describe how the identity of the product that is formed in test tube A can be confirmed.

(2marks)

…………………………………………………………………………………………………………

….....

…………………………………………………………………………………………………………

….....

(b) 0.115g of Sodium metal was dropped in a trough full of water.

(i) State and explain what was observed than the production of a hissing sound. (2marks)

…………………………………………………………………………………………………………

….....

…………………………………………………………………………………………………………

….....

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…………………………………………………………………………………………………………

….....

(ii) Calculate the volume of the gas produced at r.t.p (Na = 23, molar gas volume = 24dcm3 at r.t.p)

(2 mark)

…………………………………………………………………………………………………………

….....

…………………………………………………………………………………………………………

(c) Dry hydrogen gas was passed over heated Copper (II) Oxide as shown below.

Copper (II) Oxide V

Dry hydrogen

Excess hydrogen

burns

Heat

(d) (i) Write down the equation for the reaction that takes place in the combustion tube.( 1 mark)

….…………………………………………………………………………………………………

……

………………………………………………………………………………………………………

(ii) Name another gas that would play the same role as hydrogen if passed in the combustion

tube above. (1mark)

………...………………………………………………………………………………………….....

………...………………………………………………………………………………………….....

(iii) Describe how the purity of the product formed by the burning at V can be confirmed.

(2marks)

………...………………………………………………………………………………………….....

………...………………………………………………………………………………………….....

5. (a) The diagram below was used to prepare a gas X in the laboratory. Study it and answer the

questions that.

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(i) Name gas X (1mark)

………...………………………………………………………………………………………….....

(ii) Write an equation to show the production of gas X. (1mark)

………...………………………………………………………………………………………….....

(b) Study the scheme diagram below and answer the questions that follow.

(i) Name the catalyst that is suitable to carry out the reaction in Step I. (1mark)

………...………………………………………………………………………………………….....

………...………………………………………………………………………………………….....

(ii) Name the process that takes place in Step II. (1mark)

………...………………………………………………………………………………………….....

………...………………………………………………………………………………………….....

(iii) State the conditions necessary for the reaction in Step III to occur. (1mark)

………...………………………………………………………………………………………….....

………...………………………………………………………………………………………….....

(iv) Write down the equation for the reaction that takes place in Step IV (1 mark)

………...………………………………………………………………………………………….....

………...………………………………………………………………………………………….....

Ethanol

C2H6 Ethene [-CH2-

CH2-]n

CH3CH2Cl

Step I

Step IV

Step II Step III

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(c) Other than using burning, describe how you would distinguish between ethane and ethyne.

(3marks)

………...………………………………………………………………………………………….....

………...………………………………………………………………………………………….....

………...………………………………………………………………………………………….....

………...………………………………………………………………………………………….....

(d) (i) What are isomers? ( 1mark)

………...………………………………………………………………………………………….....

………...………………………………………………………………………………………….....

(ii) Draw and name all structures of all the isomers of the compound with molecular formula C4H8

(3 marks)

………...………………………………………………………………………………………….....

………...………………………………………………………………………………………….....

………...………………………………………………………………………………………….....

………...………………………………………………………………………………………….....

………...………………………………………………………………………………………….....

………...………………………………………………………………………………………….....

5. (a) The scheme below shows the industrial manufacture of sulphuric (VI) acid. Study it and answer

the questions that follow.

(i) Name the chamber A. (1mark)

………...………………………………………………………………………………………….....

………...………………………………………………………………………………………….....

(ii) Explain why concentrated Sulphuric (VI) acid is used in the absorption chamber and not water.

(1mark)

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………...………………………………………………………………………………………….....

………...………………………………………………………………………………………….....

(iii) Write down the equation for the reaction that takes place at the absorption chamber

(1mark)

………...………………………………………………………………………………………….....

………...………………………………………………………………………………………….....

(iv) Name two catalysts that can be used in the catalytic chamber. (1mark)

………...………………………………………………………………………………………….....

………...………………………………………………………………………………………….....

………...………………………………………………………………………………………….....

………...………………………………………………………………………………………….....

(b) Sulphuric (VI) acid is used in making fertilizers. What volume of ammonia gas will be required

to make 25kg of ammonium sulphate? (N = 14, H = 1.0, S = 32, O = 16.0

molar gas volume at r.t.p = 24.0dm3) ( 3 marks)

………...………………………………………………………………………………………….....

………...………………………………………………………………………………………….....

………...………………………………………………………………………………………….....

………...………………………………………………………………………………………….....

(c) State and explain what is observed when concentrated Sulphuric (VI) acid is placed in a test tube

containing.

(i) Cane sugar ( 2 marks)

………...………………………………………………………………………………………….....

………...………………………………………………………………………………………….....

………...………………………………………………………………………………………….....

………...………………………………………………………………………………………….....

(ii) Sulphur and the mixture is warmed (2 marks)

………...………………………………………………………………………………………….....

………...………………………………………………………………………………………….....

………...………………………………………………………………………………………….....

………...………………………………………………………………………………………….....

(iii) State two harmful effectsSulphur (IV) Oxide has on the environment. (1 mark)

………...………………………………………………………………………………………….....

………...………………………………………………………………………………………….....

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………………………………………………………………………………………………………..

7. (i) What do you understand by the word allotropy? ( 1mark)

………...………………………………………………………………………………………….....

………...………………………………………………………………………………………….....

(ii) Diamond and graphite are naturally occurring allotropes of carbon. Explain why graphite

conducts electricity while diamond does not ( 1mark)

………...………………………………………………………………………………………….....

………...………………………………………………………………………………………….....

(iii) Name one synthetic allotrope of carbon (1mark)

………...………………………………………………………………………………………….....

………...………………………………………………………………………………………….....

(b) The diagram below shows part of the set up that can be used to prepare Carbon (IV) Oxide in the

Laboratory

(i) Write down the equation for the reaction that takes place inside the flat bottomed flask.(1 mark)

………...………………………………………………………………………………………….....

………...………………………………………………………………………………………….....

(ii) Complete the diagram to show how a reasonably pure sample of the gas is collected.

(3marks)

(c) The diagram below shows the main stages of the Soway process.

Carbon (IV)

Oxide

Brine

NH4Cl (aq)

and

NaHCO3 (S) Step I

Step

II

Substance A

NH4Cl

(aq)

NaHCO

3

Na2CO3(S) Step III

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(i) Name the substance A (1 mark)

………...………………………………………………………………………………………….....

………...………………………………………………………………………………………….....

(ii) Write the equation for the reaction that takes place in Step III ( 1mark)

………...………………………………………………………………………………………….....

………...………………………………………………………………………………………….....

(iii) Name the process in Step II ( 1mark)

………...………………………………………………………………………………………….....

………...………………………………………………………………………………………….....

(c) A mixture contains 12.39g of both Sodium Hydrogen Carbonate and Sodium Carbonate. When

the

mixture was heated to constant mass 1 dm3 of Carbon (IV) Oxide was produced at r.t.p.

Calculate the percentage composition of Sodium Carbonate in the mixture.

(2 marks)

(Na = 23, H = 1.0, C = 12.0, O = 16.0)

………...………………………………………………………………………………………….....

………...………………………………………………………………………………………….....

………...………………………………………………………………………………………….....

………...………………………………………………………………………………………….....

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KCSE MOCK 3

233/1

CHEMISTRY PAPER 1

TIME: 2 HOURS

1. Study the diagram and answer the questions that follow. The diagram shows the method of

separating components of mixture Q.

(i) State the role of the part labeled X. (1 mk)

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

(ii) State what would happen if the water inlet and water outlet in the Liebig condenser is

interchanged. (1 mk)

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

2. (a) Define Gay – Lussac’s law. (1 mk)

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

(b) 30 cm3 of ethane were mixed with 100 cm3 of oxygen and the mixture was sparked to

complete reaction all the volume were measured at a pressured of one atmosphere and a

temperature of 250C, calculate the volume the residual gas under room temperature.

(2 mks)

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…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

3. The diagram below shows a diagram of non-luminous flame. A piece of white paper is slipped into

the region of the flame as shown in the diagram and quickly removed before it catches fire.

(a) Draw and label the piece of paper to show affected by the above flame. (1 mk)

(b) Explain why a luminous flame of a Bunsen burner produces bright yellow light. (1 mk)

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

4. A student added 50 cm3 of 1.0M aqueous sulphuric acid to 50cm3 of 2.0M potassium hydroxide and

the temperature rose by 40C.

(a) Define the term molar heat of neutralization. (1 mk)

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

(b) Calculate the molar heat of neutralization (C = 4.2 J/gk-1 density of solution – 1 g/cm3)

(2 mks)

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

5. Study the set up below and answer the questions the follow.

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(a) Identify the gas produced in the flask. (1 mk)

…………………………………………………………………………………………………..

(b) Using an equation explain the observation made in the boiling tube. (2 mks)

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

6. Hydration energy of the magnesium gaseous ion is -1920kJ/mol while the lattice energy and the heat

of solution of magnesium chloride +2493 and -155 kJ/mol respectively. Using an energy cycle

diagram, work out the hydration energy of the chloride gaseous ion. (2 mks)

7. The formula given below represents a portion of a polymer.

Draw the structure of the monomer of the polymer. (1 mk)

(a) Give the name of the polymer. (1 mk)

………………………………………………………………………………………………

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8. When potassium nitrate is heated, it produces potassium nitrite and gas C.

(a) Identify gas C. (1 mk)

…………………………………………………………………………………………………..

(b) Name the type of reaction undergone by the potassium nitrate. (1 mk)

…………………………………………………………………………………………………..

9. The chromatogram below shows the constituents of ink sample M using methylated spirit as solvent.

(a) Describe how you would obtain a solid sample of the pigment from the chromatogram above.

(2 mks)

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

(b) State one property of the red dye. (1 mk)

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

10. Calculate the number of hydrogen ions in 5 cm3 of 0.5 molar phosphoric acid. (L =6.0 x 1023)

(2 mks)

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

11. The following table shows the pH values of solutions A, B, C and D.

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Solution A B C D

pH 3 7 10 14

(i) Which solution is likely to be that of iron (III) chloride? (1 mk)

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

(ii) Which solution has the highest concentration of hydroxide? Explain. (2 mks)

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

12. The diagram below shows a structure (i) of water molecules.

(i) Name the bonds labeled. (1 mk)

a………………………………………… b…………………………..

(ii) Using dots (.) and cross(x) diagram show the bonding in the compound phosphonium ion. PH4+

(H = 1, P = 15) (1 mk)

13. A dynamic equilibrium between chromate (CrO42-) and dichromate (Cr2O7

2-) is established as shown

in the equation below.

2CrO42+

(aq) + 2Hlr(aq) Cr2O7

2-(aq) + H2O(l)

yellow orange

(a) What is mean by a dynamic equilibrium? (1 mk)

…………………………………………………………………………………………………..

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…………………………………………………………………………………………………..

(b) State and explain the observation that would be made if a few drops of concentration sulphuric

(VI) acid added to the equilibrium mixture. (1 mk)

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

14. The table below shows properties of some elements. Study it carefully and answer the questions that

follow.

Element Sodium Magnesium Phosphorus

Electrical conductivity Good Good Poor

Melting point 98 660 44 44 of 115

(a) Suggest why phosphorus has been assigned tow melting point values. (1 mk)

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

(b) Explain why the melting point of magnesium is higher than that of sodium.(1 mk)

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

15. 1.512g of metal carbonate XCO3 reacts with 20cm3 of 1.8M hydrochloric acid completely. Calculate

the relative atomic mass of element X. (C = 12, O = 16). (3 mks)

16. A wooden splint glowing on both ends was fixed as shown in the diagram. The experiment was

carried as indicated.

(a) What will be observed on the glowing splint end A and B if heating is done at the same time?

(1 mk)

…………………………………………………………………………………………………..

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…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

(b) Explain the observation in (a) above. (1 mk)

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

(c) One of the products in this experiment is useful to rocket scientist is useful to rocket when going

into space. State two ways in which the scientists use this product. (1 mk)

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

17. 30 cm3 of Hydrogen gas diffuse through a porous plug in 2 minutes. How long will 90 cm3 of

hydrocarbon gas of molecular mass 72 taken to diffuse through the same plug under same

conditions. (H = 1, C = 12). (2 mks)

18. The peak below show the mass spectrum of element Q.

Calculate the relative atomic mass of Q. (2 mks)

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

19. (i) Define solubility. (1 mk)

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

(ii) Salt Q has a solubility of 30g / 100g of water. 55g of salt Q is stirred in 65g of a solution

which contains 10g of salt Q. how much more of salt Q will dissolve in the solution.

(2 mks)

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

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…………………………………………………………………………………………………..

…………………………………………………………………………………………………..


Heat

Add Dilute

HNO3

Add excess

Add NH3 (aq)

Dilute Hcl

(i) Write the two ions present in P. (1 mk)

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

(ii) Write the equation for the reaction that forms solution B. (1 mk)

…………………………………………………………………………………………………..

(iii)Write equation for thermal decomposition of P. (1 mk)

…………………………………………………………………………………………………..

21. The table below gives information of four elements by letters A, B, C and D. study it and answer the

questions that follow. The letters do not represent the actual symbol of the elements.

Element Electron arrangement Atomic radius (nm) Ionic radius nm

A 2.8.2 0.136 0.065

B 2.8.7 0.097 0.181

C 2.8.8.1 0.203 0.133

D 2.8.8.1 0.174 0.097

(a) Which two elements have similar properties? Explain. (2 mks)

Solid P

Brown

gas

Solid A Colourles

s solution

C

Colourless

solution B

Colourless

solution

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…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

(b) Why is the ionic radius any element B greater than its atomic radius? (1 mk)

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

22. In an experiment soap solution was added to three samples of water. The table below shows the soap

solution required to form lather with 500cm3 of water before and after boiling.

Sample A Sample B Sample C

Volume of soap before water is boiled 12.4 4.0 29.0

Volume of water after water is boiled 4.0 4.0 29.0

(a) Which sample is likely to be:

(i) Temporary hard water (1 mk)

…………………………………………………………………………………………………..

(ii) Permanent hard water (1 mk)

…………………………………………………………………………………………………..

(b) Write the formula of a compound that could be present in sample A but not in sample C.

(1 mk)

23. Starting with Lead (II) oxide, describe how you can prepare a sample of lead (II) sulphate.

(3 mks)

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

24. Use the electrode potentials below to answer the questions that follow:

Mn2+(aq) + 2e- Mn(s) Eθ

= -1.19V

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Cd2+(aq) + 2e- Cd(s) Eθ

= -0.40V

(a) Determine the e.m.f. of the cell. (1 mk)

(b) Write the cell representation of the cell above. (1 mk)

…………………………………………………………………………………………………..

25. Study the reaction below and answer the questions that follow.

RNH2 + H2O ⇌ RNH3 + OB –

Identify the base in the forward reaction. Explain. (1 mk)

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

26. When hydrogen gas is passed over Lead (II) oxide in a combustion tube, Lead (II) oxide is reduced.

(a) Write an equation for the above reaction. (1 mk)

…………………………………………………………………………………………………..

(b) What observation was made in the combustion tube when the reaction was complete?

(1 mk)

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

(c) Name another gas which can be used to reduce Lead (II) oxide. (1 mk)

…………………………………………………………………………………………………..

27. Some average are bond energies given below.

Bond Bond Energy

kJ/mol

C – C 348

C – H 414

C = C 610

C – Br 28

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Br – Br 193

(a) Calculate the enthalpy of the following reaction. (2 mks)

C2H4(g) + Br2 (g) CH2Br CH2Br

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

(b) Name the type of reaction that took place in (a) above. (1 mk)

…………………………………………………………………………………………………..

28. In the last state of the Solvay process a mixture of sodium hydrogen carbonate and ammonium

chloride is formed.

(i) State the method of separation used. (1 mk)

…………………………………………………………………………………………………..

(ii) Write an equation showing how lime is slaked. (1 mk)

…………………………………………………………………………………………………..

(iii)Name the by product recycled in the above process. (1 mk)

…………………………………………………………………………………………………..

29. A compound X is made of carbon, hydrogen and oxygen whose percentage composition by mass are

62.1%, 10.3% and the rest oxygen respectively. The relative molecular mass of X is 58 (H = 1, O =

16, C = 12)

(a) Determine the empirical formula of the compound. (3 mks)

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

(b) Determine the molecular formulae of the compound. (1 mk)

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…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

30. (i) What is half life? (1 mk)

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

(ii) Complete the following nuclear equation by finding the values of X and Y. (2 mks)

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

(iii) Element Z has initial mass of 80g. After 5 years the remaining mass is 5g. What is the

half life of Z? (2 mks)

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

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KCSE MOCK 3

233/2

CHEMISTRY PAPER 2

THEORY

TIME: 2 HOURS

1. The table below shows some elements of the periodic table and their atomic numbers, atomic

masses and melting points. The letters are not the actual symbols of the elements.

Element B C D E F G H I J K

Atomic No. 7 8 19 15 2 9 6 16 12 11

Atomic mass 14 16 39 31 4 19 12 32 40 23

Melting point 0C -209 -218 63.7 44 -272 -223 Vary 113 669 98

(a) Select two elements with oxidation state of -3. (1mk)

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

(b) Which elements represents the most powerful reducing agent. Explain. (2mks)

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

(c ) How does the atomic radii of D compare with that of K. Explain. (2mks)

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

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(d) How do you compare the electrical conductivity of elements J and K. Give your reason.

(1mk)

………………………………………………………………………………………………..

………………………………………………………………………………………………….. (e) Select

two elements which when reacted with element G form a compound that conducts electricity both in

molten and in aqueous state. (1mk)

…………………………………………………………………………………………………..

(f) Explain why the melting point of H has not been given a specific value. (1mk)

…………………………………………………………………………………………………..

(g) In which group and period do D and G belong? (2mks)

D Group _______________________________

Period _______________________________

G Group________________________________

Period _______________________________

(h) Explain why the melting point of element K is higher than that of D. (1mk)

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

(i) Select one element stored in

(a) Water ___________________________________ (1mk)

(b) Paraffin _________________________________ (1mk)

2. a) Study the diagram below and answer the questions that follow.

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i) Solution in reagent Bottle A is used to absorb CO2 gas, name it and write the equation for the

reaction of CO2 and the solution. (2mks)

…………………………………………………………………………………………………..………

…………………………………………………………………………………………..

ii) Name the component removed in reagent bottle B (1mk)

…………………………………………………………………………………………………..

iii) Name 2 impurities of nitrogen collected through this method. (1mk)

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

b) Ammonia undergoes catalytic oxidation forming on a an oxide which if further oxidized to form

Nitric(V) acid as shown below

4NH3(g) + 5O2(g) 4NO(g) + 6H20(l)

4NO(g) + 2H2O(l) + 3O2(g) 4HNO3(aq)

i) If 3200 cm3 of NH3 were oxidised, calculate the volume of Nitric (V) acid produced (MGV =

24dm3, N=14, H = 1, O = 16) (2mks)

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

ii) Urea (CO(NH2)2) and NH4NO3 are nitrogenous fertilizes. Which is the most recommended

fertilizer? Show your working (2mks)

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..…………

………………………………………………………………………………………..

…………………………………………………………………………………………………..

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c) Magnesium reacts in air forming too substances.

i) Name two substances. (2mks)

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

iii) When litmus paper is added a solution of one of the product b(i) above, the litmus paper turns

blue. Using a chemical equation explain the observation (2mks)

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..…………

………………………………………………………………………………………..

iv) What is “laughing gas”? (1mk)

…………………………………………………………………………………………………..

v) Explain the chemistry of laughing gas (1mk)

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

3. Use standard potential for elements G, M, N,P and Q given below to answer the questions that

follow.

E volts

G+ (aq) + e- G(s) -2.71

M2+ (aq) + 2e- M(s) -2.37

2N+ (aq) + 2e- N2(g) 0.00

P2+ (aq) + 2e- P(s) +0.34

½ O2 (g) + e- Q (g) +2.87

(a) (i) Which element is likely to be hydrogen? Give a reason to your answer. (2mks)

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

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(ii) What is the E of the strongest oxidizing agent. (1mk)

…………………………………………………………………………………………………..

(iii) Draw a well labelled diagram of the electrochemical cell that would be obtained

when half cells of M and P are combined. (3mks)

(iv) Calculate the E value of the electric chemical cell constructed in (iii) above. (2mks)

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

(b) During the electrolysis of aqueous copper (II) sulphate using copper electrodes a current of 0.8

amperes was passed through the cell for 10hours.

(i) Write ionic equation for the reactions that took place at the cathode. (1mk)

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

(ii) Determine the change in mass of the anode which occurred as a result of the electrolysis

process. (Cu = 63.5, 1 Faraday = 96500 Coulombs) (3mks)

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

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…………………………………………………………………………………………………..

…………………………………………………………………………………………………..

4. (a) (i) What are unsaturated hydrocarbon compounds ? (1mk)

…………………………………………………………………………………………………

(ii)Give the names of the following organic compounds. (1mk)

CH3

(I) CH3 - C - CH3

CH3

………………………………………………………………………………………….

(II) CH2 CH CH2 CH CH2

…………………………………………………………………………………………

(b) The scheme below shows a series of reaction starting with propanol

(i) Name the type of reaction in steps (I) and (II) (1mk)

………………………………………………………………………………………

Solution A + H2

(g)

CH3 CH2

COOH F

CH3 CH3

Compound D + HCl

Product C + H2O (l)

CH3 CH2 CH2 OH

NaOH

H+ / KMO4 (aq) Step I

K(s)

Step (iv)

Step (iii)

1 mole of Cl2(g)

B

Conc. H2SO4 1800C

CH2 CH CH3

Butan – l –ol

Conc. H2SO4

heat

E

HCl

Step (ii)

CH3 G

CH2 - C

H n

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(ii) Write equation for the reaction that takes place in step III (1mk)

……………………………………………………………………………………

(iii) Name substances A, B , C , D , E and F (3mks)

A……………………….

B…………………………

C…………………………

D………………………..

E…………………………

F…………………………

(iv) Draw the structural fomular of compound C (1mk)

(c) (i) Name the process in step IV (1mk)

………………………………………………………………………………………...

(ii)State the type of reactions involved in formation of compound B. (2mks)

……………………………………………………………………………………….

……………………………………………………………………………………….

(iii)If the relative molecular mass of G is 35,700 determine the value of n (2mks)

(iv)Below are structures of two cleaning agents.

R – COO- Na+ X

R OSO3 – Na+ Y

(I) Identify the cleaning agent suitable for use in water containing MgCl2 (1mk)

…………………………………………………………………………………….

(II) State one disadvantages of using this cleaning agent (1mk)

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……………………………………………………………………………………..

……………………………………………………………………………………..

5. A conical flask was connected to a gas syringe by means of a stopper and a delivery tube. 30cm3

of water and 0.5g of Manganese (IV) Oxide were placed in the flask and the 5cm3 of Hydrogen

Peroxide were added. The flask was quickly stoppered and the readings of volume of gas in

syringe were recorded after every 10 seconds. The results obtained were recorded in the table

below.

Time (sec) 0 10 20 30 40 50 60 70 80

Volume (cm3) 0 18 30 40 48 53 57 58 58

(a) (i) Draw a set-up used to carry out the above experiment. (3mks)

(ii) Name the gas evolved in this reaction. (1mk)

…………………………………………………………………………………………….

(b) (i) Plot a graph of volume (cm3) shown in the syringe against time (sec). Label the curve A.

(3mks)

(ii) Without emptying the flask another 10cm3 of water and 5cm3 of Hydrogen

peroxide were added and the experiment repeated exactly as above. Using the same axes as

in (b) (i) above, sketch a second curve to show how volume of gas collected would vary with

time. In this second experiment label the curve B. (1mk)

(iii) Calculate the rate of the reaction at the 30th second. (2mks)

………………………………………………………………………………………………………

………………………………………………………………………………………………………

………………………………………………………………………………………………………

………………………………………………………………………………………………………

………………………………………………………………

(c) At the end of the experiment Manganese (iv) oxide were removed from the flask, dried and re-

weighed. State the observation in the change in mass. (1mk)

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………………………………………………………………………………………………………

………………………………………………………………………………………………………

………………………………………………………………………………

(d) Nitrogen (iv) Oxide (NO2) was collected in a transparent glass jar at room temperature. The gas

jar was sealed. A chemical equilibrium established in the gas jar as represented by the chemical

equation below:

2NO2(g) N2O4(g) ∆Hø

ƒ = +9.7kJmol-1

Red/Brown (Yellow)

State and explain the observation made when the sealed glass jar is lowered in a trough of ice

cold water. (2mks)

………………………………………………………………………………………………………

………………………………………………………………………………………………………

………………………………………………………………………………

6. (a) Clean iron filings were weighed and then placed on a watch glass containing water as

shown in the following diagram.

(i) State the observation made on the iron filings after three days. (1mk)

………………………………………………………………………………………………………

………………………………………………………………………………………

(ii) With a reason compare the mass of the iron filings at the start of the experiment with that of

the product after three days. (2mks)

………………………………………………………………………………………………………

………………………………………………………………………………………

(iii) Give the general chemical formula of the product formed in this experiment. (1mk)

………………………………………………………………………………………………

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(iv) An ore is suspected to contain iron metal, describe how the presence of iron in the ore could

be confirmed. (3mks)

………………………………………………………………………………………………………

………………………………………………………………………………………………………

………………………………………………………………………………………………………

………………………………………………………………………………………………………

………………………………………………………………………………………………………

………………………………………………………

(b) (i) Name one ore from which iron is extracted. (1mk)

………………………………………………………………………………………………

(ii) What is the name of the process used in the extraction of iron metal in the blast furnace.

(1mk)

………………………………………………………………………………………………

(iii)The following diagram represents the blast furnace, in which extraction of iron is carried

out,

(i) Identify one other raw material used apart from the iron ore. (1mk)

………………………………………………………………………………………………

(ii) Write the equations that lead to the formation of substance A in the blast furnace. (1mk)

………………………………………………………………………………………………………

………………………………………………………………………………………

(iii) State one property of the iron produced on the blast furnace. (1mk)

………………………………………………………………………………………………………

………………………………………………………………………………………

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7. Study the flow chart below and use it to answer the questions that follow.

Step3 NaOH Excess NaOH

BaCl2(aq) Step 1

Excess NH3(aq) Step 2

HCl

a) Identify the cation and anion in solution K.

i) Cation ....................................................................................................................................... (lmk)

ii)Anion ........................................................................................................................................ (lmk)

b) i) Name precipitate L…………………………....... (lmk)

ii) Write the ionic equation for the formation of precipitate L. (1mk)

……………………………………………………………………………………………

c) i) Name the type of reaction in step 2. (lmk)

……………………………………………………………………………………………

ii) Write a balanced equation for the reaction in step 2. (1mk)

……………………………………………………………………………………………………… iii)

Name any other solution that can be used in step 2 above. (1mk)

………………………………………………………………………………………………………

d) Write the formula for the complex ion in solution M. (1mk)

………………………………………………………………………………………………………

e) i) Write the ionic equation for the reaction in step 3. (1mk)

………………………………………………………………………………………………………

ii) Write the chemical equation in step 3. (1mk)

………………………………………………………………………………………………………

White ppt T Solution K

White ppt L

White ppt L Colourless

Solution M

Colourless

Solution W

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KCSE MOCK 4

233/1

CHEMISTRY

Theory

Paper 1 Time: 2 Hours

1. Study the set-up shown below and use it to answer the questions that follow.

(a) State the observations made at the end of the experiment on:

(i) The cobalt II chloride papers. (1 mark)

(ii) Copper II oxide powder. (1 mark)

(b) (i) Why was excess hydrogen ignited? (1 mark)

Copper

oxide Liquid droplets

Flame

Point(s)

Dry hydrogen

gas

Heat

Clamp

Anhydrous cobalt II

Chloride

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(ii) Write a fully balanced equation for the reaction occurring at the flame

at point(s). (1 mark)

2. A student used the reaction between steam and heated magnesium metal to collect a dry sample

of hydrogen gas. Complete the diagram to collect the gas. (3 marks)

Write the equation for the reaction producing the hydrogen gas in the above reaction.

(1 mark)

3. The following diagram represents a set-up showing how changes of state from solid to liquid

could be investigated.

Heat

Glass wool

soaked in water

Heat

Magnesium ribbon

Q

P

Water Beaker

Boiling tube

Heat

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(a) Identify the apparatus P and Q and state their uses. (2 marks)

P -

Q -

4. (a) Define the term “Gay Lussac’s law”. (1 mark)

(b) When 100cm3 of gaseous hydrocarbon (Cx Hy) burn in 400cm3 of oxygen,

100cm3 of oxygen is unused, 200cm3 of steam are formed. Deduce the equation for the

reaction and the formula of the hydrocarbon. (2 marks)

5. If it takes 30 seconds for 100cm3 of carbon (IV) oxide to diffuse across a porous plate. How long

will it take 150cm3 of nitrogen (IV) oxide to diffuse across the same plate under similar

conditions? (C = 12.0, N = 14.0, O = 16.0) (2 marks)

6. Define Charles’ law. (1 mark)

7. The table below shows the solubility of a salt at various temperatures.

Temperature oC Solubility (g/100g water)

0 36

40 30

80 25

100 22

120 20

(a) Define the term fractional crystallization. (1 mark)

(b) A saturated solution of the salt at 400C was heated to 1000C. State and

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explain the observation made. (2 marks)

(c) Calculate the mass of salt formed when a saturated solution of the salt at 00C is placed in

a water bath maintained at 1000C. (1 mark)

8. The structures below are a representation of cleansing agents M and N.

R

(i) Identify the agents. (1 mark)

M -

N -

(ii) Write an equation for the compound formed when agent N is used with water containing

calcium nitrate salt. (1 mark)

(iii) A water engineer analyzed water from a borehole and found out that it contained

magnesium chloride impurities. State any two methods used to make the water suitable

for washing using agent N. (1 mark)

9. Calculate the percentage abundance of two other isotopes of element A with three isotopes, (30,

32, 35). Given that the R.A.M is 30.5 and percentage abundance of 35 is 5%.

(2 marks)

M

N

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10. An element Z has ionic configuration of The element is burned in excess oxygen and

the product is then added to water. Write two possible equation for the reactions which took

place. (2 marks)

11. Phosphorus (III) oxide has a lower melting point than calcium chloride. Explain.

(2 marks)

12. Describe how you would prepare silver carbonate starting with silver. (3 marks)

13. Use the table below to determine the enthalpy change for the reaction between hydrogen and

chlorine. (3 marks)

Bond Bond Energy kJ/mole

H – H 435

H – Cl 431

Cl – Cl 244

14. Explain why hydrogen sulphide cannot be used as a fuel, though it can burn to give out useful

heat energy. (1 mark)

15. (a) Explain why cryolite is added to aluminium oxide before electrolysis.

(1 mark)

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(b) During electrolysis 40,000 amperes was passed through a Hall cell for 10 hrs. Calculate

the mass of aluminium deposited at the cathode in kg.

(IF = 96500C, Al = 27) (3 marks)

16. (a) Define the term half-life. (1 mark)

(b) A certain nuclide has a half-life of 2.5 hours. What percentage of a given mass of the

nuclide will be left after 7.5 hrs? (2 marks)

17. Explain how increase in temperature affects the rate of a given reaction.

(2 marks)

18. Write down the preliminary steps undertaken to concentrate an ore during extraction of metals.

(2 marks)

19. Write down the formula of the chief ore of Aluminium. (1 mark)

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20. Dilute sulphuric (VI) acid was added to a compound P of magnesium. The solid reacted with the

acid to form a colourless solution Q and a colourless gas R which formed a white precipitate

when bubbled through lime water. Identify:

(1 ½ marks) (a) compound P -

(b) solution Q -

(c) colourless gas R -

21. During an experiment on the reduction of an oxide of copper, the following data was obtained.

Mass of empty boat = 25.0g

Mass of empty boat + oxide of copper = 29.0g

Mass of boat + copper (after reaction) = 28.2g

Determine the empirical formula. (3 marks)

(Cu = 64, O = 16)

22. Calculate the number of atoms in 26.4g of calcium carbonate.

(Ca = 40, C = 12, O = 16, L = ) (2 marks)

23. Lead (II) nitrate was heated completely.

(a) Write an equation for heating lead (II) nitrate. (1 mark)

(b) Calculate the mass of the oxide formed given that 0.2 moles of the nitrate was heated. (Pb

= 207, O = 16) (2 marks)

24. Draw and name two branched isomers of the compound whose chemical

formula is . (2 marks)

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25. (a) Complete the following table based on organic compounds. (1 mark)

Compound Reagents needed for preparation

(i) Ethyne

(ii) Ethane

(b) Write chemical equations to represent the reaction in (a) above.

(2 marks) (i)

(ii)

(c) An organic substance (Q) reacted with ethanoic acid to form pleasant smelling compound

.

(i) What conditions will be required to form the product? (1 mark)

(ii) If another compound with a chemical formulas has to be formed from

compound Q, what would be the conditions required in this process.

(1 mark)

26. (a) Give the formula of the Monomer used during the formation of the following

polymer. (1 mark)

H H H H

C C C C

Cl H Cl H

(b) State any use of the polymer in (a) above. (1 mark)

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(c) Other than using universal indicator explain how one can differentiate between the

following chemicals.

Propanol and propanoic acid. (1 mark)

27. The melting points of oxygen and sulphur are -2160C and 1130C respectively yet the two

elements belong to group VI in the periodic table. Explain. (2 marks)

28. Which type of Sulphur is formed under the following conditions?

Conditions Type of Sulphur

(i) Above 960

( ½ mark)

(ii) Pouring boiling Sulphur into cold water

( ½ mark)

(iii) Rapidly cooling Sulphur vapour

( ½ mark)

(iv) Mixing sodium thiosulphate with dilute

hydrochloric acid

( ½ mark)

29. When dry chlorine is passed over heated iron in a combustion tube, a brown solid forms on the

cooler parts of the combustion tube.

(i) Name the brown solid. (1 mark)

(ii) Why does the brown solid form on the cooler parts of the combustion?

(1 mark)

(iii) What will be the pH of the solution formed when the brown solid is dissolved in water?

(1 mark)

(iv) Chlorine gas is poisonous yet it is used to treat water. Explain. (1 mark)

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30. The diagrams below show the apparatus used to investigate one of the properties of carbon.

State and explain the observations made in each boiling tube. (2 marks)

31. The diagrams below show the apparatus used to investigate the properties of carbon IV oxide

gas.

(i) State and explain the observations made in each gas jar. (2 marks)

(ii) State one industrial use of carbon (IV) oxide. (1 mark)

Boiling tube A Boiling tube B

Copper II oxide /

carbon mixture Aluminium

oxide / carbon

mixture

Gas Jar Q

CO2(g)

Burning

Mg

Gas Jar X

Carbon IV

oxide

Burning sulphur

Deflagrating

spoon

Heat Heat

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KCSE MOCK 3

233/2

CHEMISTRY PAPER 2

THEORY

TIME: 2 HOURS

1. Below is part of periodic table with elements shown. The letters are not actual chemical

symbols. Use it to answer question that follow.

P C D E

F G B H

Z

(i) What is the most likely nature of the solution formed by the oxide of Z? (1mk)

…………………………………………………………………………………………………

…………………………………………………………………………………………………

…………

(ii) Chose a letter representing the most electronegative element. (1mk)

…………………………………………………………………………………………………

…………………………………………………………………………………………………

…………

(iii) Write a balanced equation for the reaction between B and oxygen. (1mk)

…………………………………………………………………………………………………

…………………………………………………………………………………………………

…………

(iv) Compare the reactivity of C and D. Explain your answer (2mks)

…………………………………………………………………………………………………

…………………………………………………………………………………………………

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(v) An element Q has mass number 40 and 22 protons. What is the position of Q on the grid?

(1mk)

……………………………………………………………………………………………

..…………………………………………………………………………………………………

.

(b) Study the information given and use it to answer the questions that follow

Formula NaCl MgCl2 AlCl3 SiCl4 PCl3 SCl2

Boiling point (0C) 1470 1420 ___ 60 75 60

Melting point (0C) 800 710 Sublimes at

1800C

-70 -90 -80

(i) Name the physical state of SiCl4 at room temperature (1mk)

…………………………………………………………………………………………………

…………………………………………………………………………………………………

…………

(ii) Although Aluminium and magnesium are metals, AlCl3 has a much lower melting point

than MgCl2. Explain this observation. (2mks)

…………………………………………………………………………………………………

…………………………………………………………………………………………………

…………

(iii) Explain why the melting point of SiCl4, PCl3 and SCl2 are low. (1mk)

…………………………………………………………………………………………………

………….………………………………………………………………………………………

…………

2. The table below gives reduction potentials obtained when half cells are connected to a standard

half cell. Study it to answer questions that follow.

Electrode reactions E°/volts

V2+(aq) + 2e- V(s) +0.56

X+(aq) + e - X(S) -2.97

Y+(s) + e- Y(s) 2.71

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W+(aq) + e- W(S) +0.80

Z2+(aq) + 2e- Z(s) -2.85

R2+(aq) 2e- R(s)

-0.76

2P+ + 2e- P2(s) 0.00

a) Select two half cells which would produce the highest e.m.f. Determine the e.m.f that

would be produced. (2mks)

…………………………………………………………………………………………………

…………………………………………………………………………………………………

…………

b) Write down the cell representation of the cell formed in (a) above. (1mk)

………...………………………………………………………………………………………

……..

c) From the standard electrode potentials given select any two elements that can be used

as the sacrificial metal in electroplating of R. (2mks)

…………………………………………………………………………………………………

…….

………....………………………………………………………………………………………

……..

d) A steady current of 0.2A was passed through solution of X and Y ions for 2 hours.

16g of X and 0.0474g of Y were deposited.

(i) Determine the relative atomic mass of X if the formula of chloride of X is XCI

(F 6500C, Y = 63.5) (3mks)

…………………………………………………………………………………………………

…………………………………………………………………………………………………

…………

…………………………………………………………………………………………………

…………………………………………………………………………………………………

…………

…………………………………………………………………………………………………

…………………………………………………………………………………………………

…………

(ii) Hence or otherwise determine the charge on Y. (l mk

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…………………………………………………………………………………………………

…………………………………………………………………………………………………

…………

e) State one use of a salt bridge, (1 mk)

………..…………………………………………………………………………………………

3. In an experiment, 1.0 grams of an alloy of copper and magnesium were reacted with excess 4M

hydrochloric acid, and the gas collected measured at different time intervals. The results were

recorded as shown below.

a) (i) Write an equation for the chemical reaction taking place.

(1mk)

Time in minutes Total volume of gas in / cm3

0 0

1 220

2 410

3 540

4 620

5 640

6 640

7 640

ii) Plot a graph of the volume of the gas (verticals axis) against time ( horizontal axis)

(3mks)

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(b) Using the graph determine

i) The rate of reaction at 2 ½ minutes. (1mk)

………………………………………………………………………………………………..

…..……………………………………………………………………………………………

ii) The volume of the gas at the end of 3 ½ minutes. (1mk)

……………….………………………………………………………………………………..

…………..…………………………………………………………………………………….

c) The synthesis of ammonia from nitrogen and hydrogen is carried out in the Haber

process using the equation below.

N2(g) + 3H2 2NH3(g) H°=-92kJ mol-1

(i) What information is given by the thermochemical equation above?

(1mk)

………………………………………………………………………………………..

…..…………………………………………………………………………………….

(ii) Explain how an increase in temperature would affect other yield of ammonia.

(2mks)

………………………………………………………………………………………..

…..…………………………………………………………………………………….

(iii) Explain how can a increase in pressure would affect the equilibrium of the

mixture. (2mks)

………………………………………………………………………………………..

…..…………………………………………………………………………………….

………………………………………………………………………………………..

…..…………………………………………………………………………………….

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4. Study the scheme below and answer the questions that follow.

(a) State the sources of the substance X and Y. (2mks)

……………………………………………………………………………………………….…

……….…………………………………………………………………………………………

…………

(b) Identify the catalyst used in step I and how it is made to be effective. (1mk)

……………………………………………………………………………………………….…

…………..………………………………………………………………………………………

………..

(c) Name the substance A, B, C and E. (2mks)

A……………………………………………………………………………………………..

B……………………………………………………………………………………………...

C……………………………………………………………………………………………...

E……………………………………………………………………………………………...

(d) Write the chemical equations that shows

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…………………………………………………………………………………………………

…...

…..………………………………………………………………………………………………

…..

(i) The formation of substance C. (1mk)

……………………………………………………………………………………………….…

………….………………………………………………………………………………………

…………

(ii) The reaction between substance C and copper metal. (1mk)

……………………………………………………………………………………………….…

…………………………………………………………………………………………………

….………………………………………………………………………………………………

………………..

(e) Describe a chemical test for gas E. (1mk)

……………………………………………………………………………………………….…

…………………………….……………………………………………………………………

…………

……………………………………………………………………………………………….…

……………………..……………………………………………………………………………

…………

(f) (i) State one economic use of substance F. (1mk)

……………………………………………………………………………………………….…

………….………………………………………………………………………………………

…………

(ii) Name the optimum conditions for the production ammonia gas. (1mk)

……………………………………………………………………………………………….…

…………..………………………………………………………………………………………

………..

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5. (a) Study the diagram below and use it to answer the questions that follow.

(i) Name liquid:

P…………………………………………………………………………. (1mk)

M………………………………………………………………………… (1mk)

(ii) What is the function of concentrated sulphuric(VI) acid in the set-up? (1mk)

…………………………………………………………………………………………………

…………………………………………………………………………………………………

………….

(iii) Suggest a suitable reagent that can be used as solid W. (1mk)

…………………………………………………………………………………………………

…………………………………………………………………………………………………

………….

(iv) State the role of solid W in the set-up. (1mk)

…………………………………………………………………………………………………

…………………………………………………………………………………………………

………….

(v) Explain why solid Q collect further away from heated aluminium metal. (1mk)

…………………………………………………………………………………………………

…………………………………………………………………………………………………

………….

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(vi) In the reaction above, 0.645g of aluminium metal reacted completely with 1800cm3 of chlorine

gas at room temperature. Determine the molecular formula of solid Q, given that its relative formula

mass is 267 (Al = 27.0, Cl = 35.5, molar volume of gas at r.t.p. is 24.0 litres)

(3mks)

……………………………………………………………………………………………….………….

.……………………………………………………………………………………………….…………

…………………………………………………………………………………………….……………

………………………………………………………………………………………….………………

……………………………………………………………………………………….…………………

…………………………………………………………………………………….……………………

………………………………………………………………………………….………………………

……………………………………………………………………………….…………………………

………………………………………

(b) The flow chart below shows part of an analysis of a mixture that contains two salts.

(i) What condition is necessary for the process in step I to take place? (1mk)

…………………………………………………………………………………………………

……

(ii) Draw a well labeled set-up of apparatus that could be used to separate the mixtures

formed in step II. (2mks)

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(a) Use the bond energies given in the table below to calculate the enthalpy change for the

reaction. C2H6 (g) + Br2 (g) C2H5Br(g) + HBr(g)

(2mks)

Bond C – H C – Br Br – Br H – Br

Bond energy kJ/mol 413 280 193 365

……………………………………………………………………………………………….………….

.……………………………………………………………………………………………….…………

…………………………………………………………………………………………….……………

………………………………………………………………………………………….………………

……………………………………………………………………………………….…………………

…………………………………………………………………………………….……………………

………………………………………………………………………………….………………………

……………………………………………………………………………….…………………………

………………………………………

(b) Hydrogen peroxide decomposes according to the equation given below;

H2O2 (l) H2O(l) + ½ O2 (g) ; ΔH = -98 kJ/mol

If 6.8g of hydrogen peroxide contained in 75 cm3 of solution with water were completely

decomposed, determine the rise in temperature due to the reaction.

(2mks)

(Specific heat capacity of water = 4.2 Jg-1K-1, density of water = 1 g/cm3, O = 16, H = 1)

……………………………………………………………………………………………….…………

…………………………………………………………………………………….……………………

………………………………………………………………………….………………………………

…………………………………………………………………………………………………………

…………………….

(c) On the space provided below sketch the cooling curve that would be obtained when a

boiling tube containing water at 80oC is immersed in a freezing mixture maintained at -10oC.

(3mks)

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(d) Butane C4H10 cannot be prepared directly from its elements but its standard heat of formation

(ΔHθf) can be obtained indirectly. The following heats of combustion are given.

ΔHθC carbon (s) = -393 kJ/mol

ΔHθC H2 (g) = -286 kJ/mol

ΔHθC C4H10 = -2877 kJ/mol

(i) Draw an energy cycle diagram linking the heat of formation of butane with its heat of

combustion and the heat of combustion of its constituent elements. (2mks)

(ii) Calculate heat of formation of butane ΔHθf (C4H10). (2mks)

……………………………………………………………………………………………….…………

…………………………………………………………………………………….……………………

…………………………………………………………………………………………………………

………………

(e) Given that the lattice enthalpy of potassium chloride is +690 kJ/mol and hydration enthalpies

of K+ and Cl- are -322 kJ and -364 kJ respectively. Calculate the enthalpy of solution of potassium

chloride. (2mks)

……………………………………………………………………………………………….…………

…………………………………………………………………………………………………….……

………………………………………………………………………………………….………………

…………………………………………………………………………………………………………

……………………..

6. a) An aqueous solution of hydrogen peroxide decomposes according to the equation

2H2O2(l) 2H2O(l) + O2(g)

This reaction is fast at 200C in the presence of manganese (IV) oxide.

(i) What is the role of manganese (IV) oxide in the reaction. (1mk)

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…………………………………………………………………………………………………………

…………………………………………………………………………………………………………

………….

(ii) Sketch graphs on the same grid provided below showing how the volume of oxygen

(vertical axis) varies with

I. Time when 0.5g of manganese (IV) oxide is mixed with; 100cm3 hydrogen peroxide

solution, label this curve A.

(1mk)

II. Time when the same experiment is repeated at 300C, label this curve B.

(1mk)

(b) (i) Write the equation for the manufacture of ammonia hence explain how the increase in

pressure affects the position of the equilibrium.

(2mks)

…………………………………………………………………………………………………

…………………………………………………………………………………………………

…………………………………………………………………………………………………

…………………………………………………………………………………………………

……………………

(ii) The reaction in b(i) above is exothermic, what is the effect of raising temperature on the

equilibrium position?

(1mk)

Time

Volu

me

of

oxygen

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…………………………………………………………………………………………………

…………………………………………………………………………………………………

…………

6. a) Give the names of the following compounds.

(i) CH3CH2CH2CH2OH .………………………………………………………

(1mk)

(ii) CH3-COO-CH2-CH3……………………………………………………….. (1mk

b).One of the two formulae in (a) above represents a sweet smelling compound. Give the

names of the two organic compounds that can be used to prepare this compound in the

laboratory. (2mks)

…………………………………………………………………………………………………

…#………………………………………………………………………………………………

…………………………………………………………………………………………………

………………

c), Ethane and Ethene react with Bromine according to the following equations given below:

i. glgg HBrBrHCBrHC 52262

ii. lgg BrHCBrHC 242242

Name the type of bromination reaction taking place in

(i)……………………………………………………………………………… (1mk)

(ii)……………………………………………………………………………. (1mk)

d) A certain polymer has the following structure

CH CH2 CH CH2

C5H5 C6H5

What is meant by polymerization? (1mk)

…………………………………………………………………………………………………

…………………………………………………………………………………………………

…………

n

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KCSE MOCK 5

233/1

CHEMISTRY

PAPER 1

THEORY

TIME: 2 HOURS

1. Study the figure below and answer questions that follow.

Name the parts labelled F and G.

(1mk)

F:…………………………………….

G:……………………………………….

2. The table below gives information on four elements represented by K, L, M and N. Study it and answer

the questions that follow. The letters do not represent the actual symbols of the elements.

Element Electron arrangement Atomic radius Ionic radius

K 2, 8, 2 0.136 0.065

L 2, 8, 7 0.099 0.181

M 2, 8, 8, 1 0.203 0.133

N 2, 8, 8, 2 0.174 0.099

(a) Which two elements have similar chemical properties? Explain.

(2mks)

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

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……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

………………………………………….

3. Describe how a solid sample of Lead (II) Chloride can be prepared using the following reagents:

Dilute Nitric Acid, Dilute Hydrochloric Acid and Lead Carbonate.

(3mks)

………………………………………………………………………………………………………………

…………….…………………………………………………………………………………………………

………………………………………………………………………………………………………………

………………………………………………………………………………………………………………

………………………………………………………………………………………………………………

………………………………………………………………….

4. Na+(g) + Cl-(g) NaCl(s) ΔH1 = -781KJmol-1

H2O(l)

NaCl(s) Na+(aq) + Cl-

(aq) ΔH2 = +7KJmol-1

(a) What is the name of ΔH1?

(1mk)

……………………………………………………………………………………………………………

…………..

(b) Calculate the heat change for the process:

(2mks)

H2O(l)

Na+(aq) + Cl-

(aq) Na+(aq) + Cl-

(aq)

5. The table below gives the solubility of potassium bromide and potassium sulphate at 00C and 400C.

Substance Solubility g/100g H2O at

00C 400C

Potassium bromide 55 75

Potassium sulphate 10 12

When an aqueous mixture containing 60g of potassium bromide and 7g potassium sulphate in 100g of

water at 800C was cooled to 00C, some crystals were formed.

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(a) Identify the crystals.

(1mk)

……………………………………………………………………………………………………………

………...

(b) Determine the mass of the crystals.

(1mk)

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………

6. The graph below shows the amount of calcium carbonate and calcium chloride varying with time in the

reaction.

CaCO3(s) + 2HCl(aq) CaCl2(aq) + H2O + CO2(g)

(a) Which curve shows the amount of calcium chloride varying with time?

(1mk)

……………………………………………………………………………………………………………

………….

(b) Explain why the two curves become horizontal after a given period of time.

(1mk)

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………

(c) Sketch on the graph, how curve II would appear if the experiment was repeated using a more dilute

hydrochloric acid solution.

(1mk)

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7. 200cm3 of Nitrogen (I) Oxide (N2O) pass through a porous plug in 2 minute 15 seconds. How long will it

take the same volume of Sulphur (IV) Oxide (SO2) gas to diffuse through the same plug under the same

conditions? (N = 14, O = 16, S = 32)

(3mks)

………………………………………………………………………………………………………………

………………………………………………………………………………………………………………

………………………………………………………………………………………………………………

………………………………………………………………………………………………………………

……………………………………………………

8. An organic compound contains carbon and hydrogen only. When this compound was completely burnt in

excess air, it gave 9.6g of Carbon (IV) Oxide and 4.9g of water vapour. The molecular mass of the

hydrocarbon is 58. Determine the molecular formula. (C = 12, O = 16, H = 1)

(3mks)

………………………………………………………………………………………………………………

………………………………………………………………………………………………………………

………………………………………………………………………………………………………………

………………………………………………………………………………………………………………

……………………………………………………

………………………………………………………………………………………………………………

………………………………………………………………………………………………………………

…………………………


Dil HNO3(aq)

Step 1

H2SO4(aq)

Step II

Step III NaCl(aq)

White solid R

Colourless odourless gas

Colourless solution

White ppt T

White ppt T

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(a) Identify solid R.

(1mk)

……………………………………………………………………………………………………………

………….

(b) Write a balanced equation for step II and ionic equation for step III.

Step II ……………………………………………………………………………………………………

(1mk)

Step III …………………………………………………………………………………………………...

(1mk)

10. In an experiment to study properties of carbon, a small amount of charcoal is placed in a boiling tube.

5.0cm3 of concentrated nitric acid is added. The mixture is then heated.

(a) What observations are made?

(1mk)

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………

(b) Write an equation for the reaction that took place in the boiling tube.

(1mk)

……………………………………………………………………………………………………………

…………

(c) What property of carbon is shown in this reaction?

(1mk)

……………………………………………………………………………………………………………

………….

11. Both diamond and graphite have giant atomic structures. Explain why diamond is hard while graphite is

soft.

(2mks)

………………………………………………………………………………………………………………

………………………………………………………………………………………………………………

………………………………………………………………………………………………………………

………………………………….

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12. (a) Define the term oxidation state.

(1mk)

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

………………………………

(b) Calculate the oxidation states of chromium and manganese in the following ions.

(2mks)

(i) Chromium in Cr2O72-

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

………………………………

(ii) Manganese in MnO4-

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

………………………


Step 1

Step 2

Polymerization

Step 3. Temp. of 1500

Nickel catalyst, H2

(a) Identify substances:

K:…………………………………………………

(½mk)

U:…………………………………………………

(½mk)

Ethanol

Ethene U

L

K

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L:…………………………………………………

(½mk)

(b) State the conditions for the reaction in step 1 to occur. (2mks)

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

………………………………

(c) Give one disadvantage of continued use of substances such as U. (½mk)

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………

14. Use the set up below to answer the questions that follow.

Green Yellow fumes

Molten PbCl2

(a) On the diagram, label the cathode.

(1mk)

(b) Write the equation for the reaction on the cathode. (1mk)

……………………………………………………………………………………………………………

15. Use the bond energy value given below for the question that follows.

Bond Bond energy (kJmol-1)

H – H 432

C = C 610

C – C 346

C – H 413

Determine the enthalpy change for the conversion of butene to butane by hydrogen. (3mks)

………………………………………………………………………………………………………………

………………………………………………………………………………………………………………

………………………………………………………………………………………………………………

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………………………………………………………………………………………………………………

………………………………………………………………………………………………………………

………………………………………………………………..

16. The peaks below show the mass spectrum of element X.

Calculate the relative atomic mass of X. (2mks)

………………………………………………………………………………………………………………

………………………………………………………………………………………………………………

…………………………

………………………………………………………………………………………………………………

17. In an experiment, concentrated sulphuric (VI) acid was put in a beaker and exposed to air for one week as

shown below.

(i) What observation was made after one week? Explain. (2mks)

…………………………………………………………………………………………………………

…………………………………………………………………………………………………………

…………………………

(ii) What property of sulphuric (VI) acid was being investigated in the experiment? (1mk)

…………………………………………………………………………………………………………

18. Below is a set-up of apparatus used to prepare hydrogen gas in the laboratory. Study it and answer the

questions that follow.

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(a) Write a chemical equation for the two reactions taking place in he above set-up. (2mks)

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

(b) State the chemical test for hydrogen gas. (1mk

…………………………………………………………………………………………………………

………………………………………………………………………………..…………………………

19. State three reasons why air is considered to be a mixture but not a compound. (3mks)

………………………………………………………………………………………………………………

………………………………………………………………………………………………………………

………………………………………………………………………………………………………………

……………………………………….

20. Study the set up below and answer the questions that follow.

(a) Identify gas X.

(1mk)

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…………………………………………………………………………………………………………

……………

(b) State the observation made in the combustion tube.

(1mk)

…………………………………………………………………………………………………………

……………

(c) Write equation for the reaction in combustion tube.

(1mk)

…………………………………………………………………………………………………………

……………

21. The set-up below shows the catalytic oxidation of ammonia in the laboratory.

Red hot platinum

Ammonia

(a) State and explain the observation made.

(2mks)

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

………………………………

(b) Write a chemical equation for the first reaction taking place in the beaker.

(1mk)

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………..

22. When sulphur is heated in a boiling tube in absence of air, the yellow crystals melts into golden yellow

mobile liquid at 1130C. The liquid changes at 1800C into a dark brown very viscous liquid. More heating

to about 4000C, produces a brownless viscous liquid.

(a) Draw the molecular structure of sulphur in the yellow crystals. (1mk

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(b) Explain why the molten liquid becomes viscous.

(1mk)

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………

(c) If the brown liquid at 4000C is cooled rapidly by pouring it into cold water, which form of sulphur is

produced? (1mk)

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………

23. An experiment was set up using chlorine water as shown below.

(i) Identify gas X. (1mk)

……………………………………………………………………………………………………………

…………..

(ii) Write an equation for the production of gas X. (2mks)

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

…………………….

24. The 1st, 2nd and 3rd ionization energies in KJ/Mol of elements G and R are given below.

Element 1st I.E 2nd I.E 3rd I.E

G 520 7,300 9,500

R 420 3,100 4,800

(i) Define the term 1st ionization energy.

(1mk)

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………………………………………………………………………………………………………

………………………………………………………………………………………………………

…………………………

(ii) Apart from the decrease in energy levels, explain the big difference between the 1st and 2nd

ionization energies. (1mk)

………………………………………………………………………………………………………

………………………………………………………………………………………………………

…………………………

(iii) Calculate the amount of energy for the process: (1mk)

R(g) R3+(g) + 3e-

25. A gaseous compound consists of 86% carbon and 14% hydrogen by mass. At s.t.p. 3.2dm3 of the

compound had a mass of 6g. Calculate its molecular formula. (1 mole of a gas at s.t.p. = 22.4dm3)

(3mks)

………………………………………………………………………………………………………………

………………………………………………………………………………………………………………

………………………………………………………………………………………………………………

………………………………………………………………………………………………………………

………………………………………………………………………………………………………………

…………………………………………………………………

26. The table below shows the pH values of some solutions.

Solution J K L M N

pH 6 13 2 10 7

(a) Which solution is likely to be:

(i) Potassium hydroxide (1mk)

…………………………………………………………………………………………………………

…………..

(ii) Lemon juice (1mk)

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…………………………………………………………………………………………………………

…………..

(b) Explain why a solution of hydrogen chloride gas in methyl benzene was identified as N.

(1mk)

…………………………………………………………………………………………………………

…………………………………………………………………………………………………………

…………………………

27. Using dots (•) and crosses (x) to represent electrons, show bonding in the compound formed when the

following elements reacts. (N = 14, H = 1).

Nitrogen and Hydrogen. (1mk)

28. Some salts may be classified as double salts or basic salts. Trona with the formula Na2CO3.NaHCO3 is an

example of a double salt. An example of a basic salt is basic magnesium carbonate with formula

MgCO3.Mg(OH)2.

(a) What is meant by a double salt? (1mk)

…………………………………………………………………………………………………………

…………………………………………………………………………………………………………

…………………………

(b) Write equations of reactions that occur when dilute hydrochloric acid is reacted with: (2mks)

(i) Trona

………………………………………………………………………………………………

………………………………………………………………………………………………

…………………..

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(ii) Basic magnesium carbonate.

………………………………………………………………………………………………

………………………………………………………………………………………………

……………………

29. During Olympics, urine sample of five short distance runners were taken and tested for the presence of

two illegal steroids by paper chromatography. Methanol was used as the solvent. A chromatogram from

the test appeared as shown below. Study the chromatogram and answer the questions that follow.

KEY

SPOT A – STEROID A

SPOT B – STEROID B

SPOT 1 – ATHLETE 1




x x x x x x x

A B 1 2 3 4 5

(a) Which of the two steroids is most likely to be more soluble in methanol? Give a reason.

(1mk)

……………………………………………………………………………………………………………

…………

(b) Identify the athletes that tested positive for the illegal steroids.

(2mks)

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………

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KCSE MOCK 5

233/2

CHEMISTRY

PAPER 2

THEORY

TIME: 2 HOURS

1. (a) Study the flow chart below and answer the questions that follow.

Step II H2(g) Ni(s) Step 1 Step VI

Step V

Polymerize

Step III HCl(g) Step IV

(i) Name the process taking place in step (I). (1mk)

…………………………………………………………………………………………………………

…………..

(ii) Describe chemical test that can be carried out to show the identity of organic compound A.

(2mks)

…………………………………………………………………………………………………………

…………..

…………………………………………………………………………………………………………

…………..

…………………………………………………………………………………………………………

…………..

A Long chain alkane

C

Propan-l-ol CH3CH2CH2OH

CH3CH = CH2

CO2(g) + H2O(l)

B

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…………………………………………………………………………………………………………

…………..

(iii) Give the name of the following: (2mks)

I. A:………………………………………………………………………………………

……………

II. B:………………………………………………………………………………………

……………

(iv) Give the structural formulae of substance C. (1mk)

…………………………………………………………………………………………………………

……………

(v) Name the type of reaction that occurs in:

I. Step IV (1mk)

…………………………………………………………………………………………

……………

II. Step

VI:………………………………………………………………………………………

……..

(vi) Give the reagent and the condition necessary for step VI. (1mk)

Reagent:………………………………………………………………………………………………

……………

Condition:………………………………………………………………………………………………

…………..

(b) Give the systematic names of the following compounds:

I. CH2CHCHCH2CH3 (1mk)

………………………………………………………………………………………………

……………

II. CH C C H3 (1mk)

………………………………………………………………………………………………

……………

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2. The flow chart below shows the Haber process in the large scale manufacture of Ammonia gas. Use it to

answer the questions that follow.

Unreacted

Gases

(a) Describe how nitrogen is obtained from air on a large scale. (3mks)

………………………………………………………………………………………….………………

………………………………………………………………………….………………………………

……………………………………………………………………………………………………………

………………………………..…………………………………………………………………………

…………………………………………..………

(b) (i) Name one source of hydrogen gas used as a raw material in the above process. (1mk)

……………………………………………………………………………………………………………

…………

(ii) Name chamber A. (1mk)

……………………………………………………………………………………………………………

…………..

(iii) Write an equation for the reaction taking place in the catalytic chamber. (1mk)

……………………………………………………………………………………………………………

…………..

(iv) In the Haber process optimum temperature of 5000C and 200 atmospheres of pressure are used to

get optimum yield of Ammonia. Why can’t lower temperatures and higher pressure be used?

(2mks)

Nitrogen Hydrogen

Purifier

Compressor 500 atmospheres

Chamber A Condenser

Liquid Ammonia

Catalytic chamber

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……………………………………………………………………………………………………………

…………..………………………………………………………………………………………………

……………………..……………………………………………………………………………………

………………………………..……

(c) Give two reasons why finely divided iron is the commonly used catalyst. (1mk)

………………………………………………………………………………………………………………………

…………………………………………………….………………………………………………………………

…………………………..

(d) State and explain the observation made when dry ammonia gas is passed over heated copper (II)

Oxide in a combustion tube. (2mks)

………………………………………………………………………………………………………………………

………………………………………………………………………………………………………………………

………………………….

(e) Give two uses of ammonia gas. (1mk)

………………………………………………………………………………………………………………………

………………………………………………………………………………………………………………………

……………………….

3. (a) In a reaction to determine the rate of a reaction between magnesium ribbon and dilute hydrochloric

acid 2g of magnesium ribbon were reacted with excess 2M hydrochloric acid. The volume of hydrogen

gas evolved was recorded at regular intervals of one minute for eight minutes. The results are as shown in

the table below.

Time (minutes) 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0

Volume of Hydrogen gas (cm3) 95 160 210 237.5 260 272.5 275 275

(i) Plot the graph of time in minutes on the horizontal axis against volume of hydrogen gas on the

vertical axis. (3mks)

(ii) Name the factor that was investigated in this experiment. (1mk)

……………………………………………………………………………………………………

…………….

(iii) Use the graph to determine the volume of hydrogen gas that was produced between 2¾ minute

and 5.0 minutes. (2mks)

……………………………………………………………………………………………………

……………………………………………………………………………………………………

……………………………………………………………………………………………………

(iv) Explain the shape of the graph between minutes 7.0 and 8.0. (2mks)

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……………………………………………………………………………………………………

……………………………………………………………………………………………………

……………………………………………………………………………………………………

………………………………………

(b) Hydrogen gas reacts with chlorine gas to form hydrogen chloride gas as shown in the equation below.

H2(g) + Cl(g) 2HCl(g)

(i) Explain the effect on the yield of HCl(g) by lowering the pressure for this reaction.

(2mks)

……………………………………………………………………………………………………

……………………………………………………………………………………………………

……………………………………………………………………………………………………

………………………………………

(ii) Using a well labeled diagram, describe how a solution of hydrogen chloride can be prepared in

the laboratory. (2mks)

4. The diagram below shows a set up which was used by student to investigate effect of electricity on solid

Molten Lead (II) Bromide. Study it and answer the questions that follow.

Cell

Switch

Bulb

Graphite Graphite Electrode

Electrode

Heat

(e) (i) State and explain the observation at the anode when the switch is switched on. (2mks)

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……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………

(ii) What precaution should be taken when carrying out this experiment? (1mk)

……………………………………………………………………………………………………

…………..

(iii) Write the equation of the reaction taking place at the Anode. (1mk)

……………………………………………………………………………………………………

……………

(iv) Why are graphite electrodes used in the experiment (1mk)

……………………………………………………………………………………………………

……………..

(v) On the diagram, indicate the direction of flow of electrons.

(vi) The students noted that the bulb only produced light after the Lead (II) Bromide had melted.

Explain this observation. (2mks)

……………………………………………………………………………………………………

……………………………………………………………………………………………………

………………………….

(f) State the difference in conduction of electric current between Molten Lead (II) Bromide and Lead

Metal.(1mk)

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

…………………….

(g) Explain why it is not advisable to store Copper (II) Sulphate solution in a can made of Zinc metal.

(2mks)

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………..

(h) State two applications of electrolysis. (1mk)

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……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………

5. (a) What is meant by molar heat of solution? (1mk)

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

…………………..

(b) The enthalpies of combustion of carbon, and carbon (II) oxide are indicated below.

C(s) + O2(g) CO2(g) : DH = 393 KJ mol-1

CO(g) + O2(g) CO2(g) : DH = 283 KJ mol-1

(i) Draw an energy level diagram that links the enthalpy of formation of Carbon (II) Oxide to

enthalpies of combustion of carbon and Carbon (II) Oxide. (2mks)

(ii) Determine the enthalpy of formation of Carbon (II) Oxide. (2mks

……………………………………………………………………………………………………

……………………………………………………………………………………………………

……………………………………………………………………………………………………

(c) The set up below was used by a student to determine the enthalpy of combustion of ethanol

(CH3CH2OH). Study it and answer the questions that follow.

Thermometer

400cm3 of distilled water

Metal Can

Flame

X

Spirit lamp containing ethanol

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The following data was collected from the experiment:

Initial temperature of water 120C

Final temperature of water 220C

Initial mass of spirit lamp 11.42g

Final mass of spirit lamp 10.50g

Specific heat capacity of water 4.20Jg-1k-1

(i) What is the function of the part labeled X. (1mk)

……………………………………………………………………………………….....................

...............

(ii) Using the data above, calculate the change in heat of combustion of ethanol, assuming density

of water is 1g/cm3. (2mks)

……………………………………………………………………………………………………

……………………………………………………………………………………………………

……………………………………………………………………………………………………

………………………………………

(iii) Calculate the molar heat of combustion of Ethanol (C = 12, O = 16, H = 1) (2mks)

……………………………………………………………………………………………………

……………………………………………………………………………………………………

……………………………………………………………………………………………………

(iv) Find the heating value of ethanol. (2mks)

……………………………………………………………………………………………………

……………………………………………………………………………………………………

……………………………………………………………………………………………………

(d) Give two precautions necessary when using fuels. (1mk)

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………

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6. (a) Starting with a solid sample of calcium carbonate, describe how a pure dry sample of calcium sulphate

can be prepared in the laboratory. (3mks)

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………

(b) The flow chart below shows a sequence of reactions involving a mixture of two salts, mixture Z.

Study it and answer the questions that follow.

Step I (i) Add distilled water

(ii) Filter

Step II Heat Step VII Add

BaCl2(aq)

and

filter

Step III Dil. Nitric (V) acid

Heat

Step V Step VI

Excess Excess

Ammonia NaOH(aq)

Solution solution

Write the formulae of the two salts present in mixture Z. (2mks)

Solid P

Mixture Z

White solid, brown gas and gas which relights glowing splint.

Colourless solution Q

Yellow solid Y which on cooling turns white and gas which forms white precipitate with lime water.

Solution V

White solid R Solution S

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……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

…………………….

(c) Write an ionic equation for the reaction in step VII. (1mk)

…………………………………………………………………………………………………………

…………….

(d) State and explain the observation in Step (V) and (VI). (3mks)

(i) Step (V) :…………………………………………………………………………………

……………………………………………………………………………………………………

……………………………………………………………………………………………………

………………………

(ii) Step

(VI):……………………………………………………………………………………………….

……………………………………………………………………………………………………

……………………………………………………………………………………………………

(e) Write an equation showing the effect of heating a sample of anhydrous copper (II) suphate in a

test tube. (1mk)

....................................................................................................................................................................

7. The grid below forms part of the Periodic Table. Use it to answer the questions that follow.

The letters do not represent the actual symbols of element.

A C M D E F

B H I J K

G

(a) (i) What name is given to the group of elements where B and G belong? (1mk)

…………………………………………………………………………………………………

……………

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(ii) Select a letter which represents an element that gain electrons most readily. Give a reason for

your answer. (2mks)

…………………………………………………………………………………………………

…………………………………………………………………………………………………

…………………………

(iii) Explain why the atomic radius of K is smaller than its ionic radius. (2mks)

…………………………………………………………………………………………………

…………………………………………………………………………………………………

…………………………

(iv) Using dots (•) and crosses(x) show the bonding between element G and M. (2mks)

(v) A carbonate of element G react with dilute sulphuric (VI) acid at s.t.p to produce 0.4dm3 of

gas. Determine the mass of G which was reacted with the acid. (Molar gas volume at s.t.p is

22.4dm3. (Relative atomic mass of G = 24 and C = 12, O = 16) (2mks)

…………………………………………………………………………………………………

……………

…………………………………………………………………………………………………

…………………………………………………………………………………………………

…………………………

…………………………………………………………………………………………………

…………………………………………………………………………………………………

…………………………

(b) Explain why sodium chloride has melting point of 10740C whereas silicon tetrachloride has a

melting point of 2030C under the same conditions.

(2mks)

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KCSE MOCK 6

CHEMISTRY THEORY

Paper 1

Time: 2 Hours

1. A polymer has the following structure.

CH2 – CH – CH2 – CH – CH2 – CH

CH3 CH3 CH3 n

(a) Draw the structure of the monomer. (1mk)

(b) A sample of the polymer is found to have molecular mass of 6426. Determine the

number of monomers present. (C = 12, H = 1). (2mks)

2. Name the catalyst used in:

(a) the decomposition of hydrogen peroxide. (1mk)

(b) the conversion of vegetable oil into margarine. (1 mk)

3. (a) Using dots (·) and crosses (x), draw the dimer structure of aluminium chloride and name the

bonds. (2mks

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b) State and explain the observation made when sodium carbonate powder is dropped into a

solution of aluminium chloride. (1mks)

4. Determine the heat of solution of potassium fluoride given that its lattice energy is +801KJ/mole

and the heats of hydration of potassium and fluoride ions are -322 and -506KJ/mole respectively.

(3mks)

5. During the extraction of aluminium, a current of 0.2 amphere was passed for one hour through the

molten aluminium oxide.

(a) Write equations for the reaction that took place at the cathode. (A1 = 27, 1F =

96500C).

(1mk)

(b) Calculate the mass of aluminium produced. (2mks)

6(a) Define Gay – Lussac’s law. (1 mk)

(b) 30 cm3 of ethane were mixed with 100 cm3 of oxygen and the mixture was sparked to

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complete reaction all the volumes were measured at a pressure of one atmosphere and a temperature

of 250C, calculate the volume the residual gas under room temperature. (2 mks)

7. The following table shows the pH values of solutions A, B, C and D.

Solution A B C D

pH 3 7 10 14

(iii)Which solution is likely to be that of iron (III) chloride? (1 mk)

(iv) Which solution has the highest concentration of hydroxide? Explain. (2 mks)

8. The table below gives information of four elements by letters A, B, C and D. study it and answer

the questions that follow. The letters do not represent the actual symbol of the elements.

Element Electron arrangement Atomic radius (nm) Ionic radius nm

A 2.8.2 0.136 0.065

B 2.8.7 0.097 0.181

C 2.8.8.1 0.203 0.133

D 2.8.1 0.174 0.097

(c) Which two elements have similar properties? Explain. (2 mks)

(d) Why is the ionic radius of element B greater than its atomic radius? (1 mk)

9. Starting with Lead (II) oxide, describe how you can prepare a sample of lead (II) sulphate. 3mks

10. When hydrogen gas is passed over Lead (II) oxide in a combustion tube, Lead (II) oxide is

reduced.

(d) Write an equation for the above reaction. (1 mk)

(e) What observations were made in the combustion tube when the reaction was complete?

(2 mk)

11. Explain why potassium is kept in paraffin while phosphorous is kept in water (2mks)

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12. Sulphur is soluble in ethanol but not in water while common salt is soluble in water but not in

ethanol

a) Explain why sulphur is not soluble in water (1mk)

b) Explain how a pure sample of sodium chloride can be obtained from a mixture of the two

(1mk)

13. Ammonia gas is prepared by Haber’s process according to the equation below

N2(g) + 3H2(g) 2NH3(g) + Heat

Complete the table below by stating the effect of equilibrium when the following conditions are

applied. Give explanation in each case

Condition Effect on equilibrium Explanation

a) Pressure increased ½ mk 1mk

b) Temperature increased ½ mk 1mk

14. State what would be observed if concentrated sulphuric (VI) acid is added to

a) Sugar crystals. (1mk)

b) Hydrated copper (II) sulphate solution (1mk)

c) What type of reaction has taken place above (1mk)

15. Name three sub – atomic particles found in an atom and state where they are found (3mks)

16. The solubility of potassium nitrate is 85g/100g of water at 50oc and 32g/100g of water at

25oc.

a) Define the term solubility. (1mk)

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b.Calculate the mass of the crystals formed if a saturated solution of potassium nitrate in 50g

of water at 50oc is cooled to 25oc. (2 marks)

17. Study the set-up below and answer the questions that follow.

Gas x

- -

- -

- -

- - - - - - - - - - - - - - - Chlorine water

- - - - - -- - - - - - - - -

a) Name gas x………………………………………………………………… ( 1 mark)

b) State the condition which is not indicated on the diagram for gas x to be formed.(1mk)

18. Calculate the mass of sulphur which on complete combustion would yield 7dm3 of sulphur (iv)

oxide measured at 182oc and 722 mm Hg pressure (0=16, S=32, molar gas volume = 24dm3 at r.t.p)

(3 marks)

19. a) State and explain the observations made when fluorine gas is bubbled through sodium

bromide solution. (2 marks)

b) When excess ammonia solution is added to a solution of copper (ii) ions, a deep blue solution

forms. Write the formula of the complex ions formed. (1 mark)

20. The following reaction is in equilibrium in a closed container

2SO2(g) + O2(g) ⇌ 2 SO3 (g) ∆H= -ve

State giving reasons how an increase in temperature would affect the amount of sulphur

(VI) oxide gas (2mk

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21. Study the diagram below and use it to answer questions that follows

(i) Identify gas R (1mk)

(ii) What changes would be observed in the test-tube (1mk)

(iii) Explain the nature of the solution formed in water after sometimes (2mks)

22. Explain the following observations

(i) electrical conductivity of metals decreases with an in increase in temperature

(2mks)

(ii) Ionization energy decreases down the group in group I (2mks)

23. M grams of a radioactive isotope decayed to 5 grams in 100 days. The half-life of the isotope

is

25 days.

(i) What is meant by half-life (1mk)

(ii) Calculate the initial mass of the radioactive isotope

(2mks)

24. Concentrated hydrochloric acid is used for removing oxides from metals (pickling). Explain

why concentrated nitric (V) acid cannot be used for the same purpose (2mks)

Heat

Zinc Nitrate

Gas R

Water

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25. The diagram below shows acidic and basic oxides fit into the general family of oxides

.

(i) State the name given to the type of oxides that would be placed in the shaded region

(1mk)

(ii) Give the names of oxides that could be placed in the shaded region (3mk)

26. Explain the following observations.

(a) A beaker with lime water, when left exposed develops a layer of a white solid on the

surface. (1 mark)

(b)Calcium chloride powder, when left exposed gradually turn into a colourless

solution.(1mark)

27. The diagram below shows a set-up intended for the electrolysis of molten lead (II) bromide.

Basic

oxide Acidic

oxide

Switch

Bulb

Lead (II) bromide

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(a) Label on the diagram: (i) anode (½ mark)

(ii) cathode (½ mark)

(b) Indicate on the diagram the direction of flow of electrons. (1 mark)

(c) State the observations made at the

(i) anode (½ mark)

(ii) cathode (½ mark)

28. The diagram below shows an experimental set-up for preparing carbon (II) oxide.

Study it and answer the questions that follow.

(a) State the role of sodium hydroxide solution in the set-up. (1 mark)

(b) State the reason why carbon (II) oxide is collected in the manner indicated.(1 mark)

(f) Describe a simple test that can be used to distinguish between carbon (II) oxide and carbon

(IV) oxide. (1 mark)

Charcoal

Heat

Sodium hydroxide solution

Combustion tube

Gas Q

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29. In an experiment to monitor the rate of reaction of zinc and hydrochloric acid a student

recorded the volume of hydrogen produced at regular time intervals and obtained the graph shown

below.

(a) On the same set of axes sketch the curve expected if the experiment is repeated with a

few crystals of copper (II) sulphate added to the reactants. (1 mark)

(b) Explain the shape of your curve. (1 mark)

Time (sec)

Volume

of hydrogen

(cm³)

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KCSE MOCK 6

CHEMISTRY THEORY

Paper2

Time: 2 Hours

1. (a) Give the names of the following compounds.

(i) CH3CH2CH2OH (1 mk)

(ii) CH3CH2COOH (1 mk)

(b) Study the information in the table below and answer the questions that follow.

No. of carbon atoms per molecule Relative molecular mass of hydrogen

2 28

3 42

4 56

(i) Write the general formula of the hydrocarbons in the table. (1 mk)

(ii) Predict the relative molecular mass of the hydrocarbon with 5 carbon atoms

(1mk

(iii) Determine the molecular formula of the hydrocarbon in (ii) and draw its

structural formula. (2 mks)

(c) Study the scheme given below and answer questions that follow.

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(i) Name the reagent used in

Step I (l mk)

Step II (1 mk)

Step IV (1 mk)

(ii) Write an equation for complete combustion of CH CH (1 mk)

(iii) Explain one disadvantage of the continued use of items in step III. (1 mk)

2. (a) The diagram below represents the extraction of sulphur by the frasch process.

(i) Identify and state the use of the substances that pass through tubes A and C.

(2mks)

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A………………………………………………………………………..

C………………………………………………………………………..

(ii) Rhombic and monoclinic are Allotropes of sulphur. They are inter convertible

as shown below.

I. What does the temperature 96°C represent. (1 mk)

II. State the differences in crystalline appearances between rhombic and

monoclinic crystals. (lmk)

(b) The following scheme represents the steps followed in the contact process, study it

and answer the questions which follow.

(i) Name three possible identities of solid A. (l mk)

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(ii) Name two impurities removed by the purifier. (1 mk)

(iii) Why is it necessary to remove impurities? (l mk)

(c) The following chemical equation shows a reaction taking place in the catalytic

chamber/converter.

(i) How would the following factors affect the production of sulphur (IV) oxide.

I Increase in temperature. (l mk)

II Decrease in pressure (1 mk

(ii) Name the catalyst which is commonly used in this process and why? (l mk)

(iii) State and explain one environmental effect of sulphur (IV) oxide in the

atmosphere.

(2mks)

3. The table below shows some elements of the periodic table and their atomic numbers, atomic

masses and melting points. The letters are not the actual symbols of the elements.

Element B C D E F G H I J K

Atomic No. 7 8 19 15 2 9 6 16 12 11

Atomic mass 14 16 39 31 4 19 12 32 40 23

Melting point 0C -209 -218 63.7 44 -272 -223 Vary 113 669 98

(a) Select two elements with oxidation state of -3. (1mk)

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(b) Which elements represents the most powerful reducing agent. Explain. (2mks)

(c ) How does the atomic radii of D compare with that of K. Explain. (2mks)

(d) How do you compare the electrical conductivity of elements J and K. Give your reason.

(1mk)

(e) Select two elements which when reacted with element G form a compound that conducts

electricity both in molten and in aqueous state. (2mk)

(f) Explain why the melting point of H has not been given a specific value. (1mk)

(g) In which group and period do D and G belong? (2mks)

D Group _______________________________

Period _______________________________

G Group________________________________

Period _______________________________

(h) Explain why the melting point of element K is higher than that of D. (1mk)

(i) Select one element stored in

(a) Water ___________________________________ (1mk)

(b) Paraffin _________________________________ (1mk)

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4. The following set – up was made in an experiment by a group of form four students. The

readings of the balance before and after experiment were indicated in the diagram below. Given that

the initial temperature of water was 26.70C respectively. The specific heat capacity of water is

4200Jkg-1k-1

Determine:

a) Temperature change that occurred (1mk)

b) Amount of ethanol used (1mk)

c) Moles of ethanol used (2mks)

d) Amount of heat gained by water (2mks)

e) Molar enthalpy of combustion of ethanol (2mks)

f) Use the following thermochemical processes to answer the questions that follow;

C3H8(g) + 5O2(g) 3CO2(g) + 4H2O(l) Hc = -125kJmol-1

C(s) + O2(g) CO2(g) Hc = - 393kJmol-1

H2(g) + ½ O2(g) H2O(l) Hc = -286kJmol-1

i) Draw an energy level diagram representing the formation and combustion processes

of propane, carbon and hydrogen (2mks)

Tripod stand

Thermometer

50cm3 of water

of density

1g/cm-3

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ii) Hence or otherwise, determine the heat of formation of propane (2mks)

5.The extraction of aluminium from its ore takes place in two stages, purification state and

electrolysis stage. The diagram below shows the set up for the electrolysis stage.

(a) (i) Name the ore from which aluminium is extracted. (1mk)

(ii) Name the impurity which is removed at the purification stage. (1mk)

(i) Label on the diagram each of the following:-

Anode (1mk)

Cathode (1mk)

Region containing electrolyte. (1mk)

(ii) The melting point of aluminium oxide is 2054oC, but electrolysis is carried out between

800oC - 900oC.

I. Why is electrolysis not carried out at 2054oC. (1mk)

II What is done to lower the temperature? (1mk)

III Give two properties that makes aluminium be collected as shown in the diagram. (2mks)

Alumimium

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(b) A typical electrolysis cell uses a current of 40,000 amperes. Calculate the mass in kg of

aluminium produced in one hour.(3mks) IF=96500c, Al=27

6. (a) In a paper chromatography sample A was found to be more soluble than sample B.

Sample C had the same solubility a sample A, while sample D was most sticky of all the samples.

Mixture K contained samples B and D only. In the space provided below draw the chromatogram of

A,B,C,D and mixture K (3 ½ mks)

(b) Using propanone describe how you can separate a mixture containing iodine crystals

and common salt (2 ½ mks)

(c)Mixture of magnesium powder and zinc (II) oxide will react vigorously when heated but no

reaction occurs when a mixture of magnesium oxide and zinc powder is heated

(i) Explain the observations made (1mk)

…………………………………………………………………………………………………

….

(ii) Write the equation for the reaction between magnesium and zinc (II) oxide (1mk)

(iii) From the reaction above identify the oxidizing agent (1mk)

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7. The diagram below shows the process of manufacturing sodium carbonate using ammonia

soda process. Study it and answer the questions that follow.

(a) Name gases A and B. (2 marks)

A

B

(b) Name liquid C and solid D. (2 marks)

C

D

(c) Write equations of the reactions in: (2 marks)

Tower P.

Chamber R.

(d) Name the product T formed at chamber R and give one of its uses. (2 marks)

(e) Explain using ionic equations how sodium carbonate is used to soften hard water. (2 marks)

Heat

Brine Solvays tower P Filter

Heating limestone

Chamber R

Chamber G Solid D

Na2CO3

Gas B Gas A

Water added

Solution C

Brine

Ammoniacal

T

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KCSE MOCK 7

233/1

CHEMISTRY

PAPER 1 (THEORY)

Time: 2 Hours

1. The figure below shows a paper that was placed horizontally across the middle of a non-luminous

flame.

a) Explain on the observation made (2 mark)

………………………………………………………………………………………………………

………………………………………………………………………………………………………

………………………………………………………………………………………………………

………………………

2. The table below shows PH values of solutions A, B, C and D.

Solution A B C D

pH 1.0 7.0 10.0 13.0

a) Which solution produces bubbles with zinc metal. Explain (2 marks)

………………………………………………………………………………………………………

………………………………………………………………………………………………………

………………………………………………………………………………………………………

………………………

Paper

Charred black

region

Unburnt region

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b) Select any pair that would react to form a solution of PH = 7 (1 mark)

………………………………………………………………………………………………………

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3. Using dot(.) and crosses (x) to represent electrons, show bounding in the compounds formed

when the following elements react (Si=14, Na=11 and C1 = 17)

a) Sodium and chloride (1 mark)

b) Silicon and chlorine (1 mark)

4. Explain why the following substances conduct electric current

a) Magnesium metal (1 mark)

………………………………………………………………………………………………………

………………………………………………………………………………………………………

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b) Molten magnesium chloride (1 mark)

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c) Aqeous sodium chloride (1 mark)

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5. The set up below was used to collect a dry sample of a gas

Calcium

oxide

CO2

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Give two reasons why the set up cannot be used to collect carbon (IV) oxide. (2

marks)

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6. A compound of carbon, hydrogen and oxygen contains 71.12% oxygen, 2.2% hydrogen and

rest carbon. If it has a relative molecular mass of 90.

a) Determine the empirical formula of the compound C = 12, 0=6 H=1 (2 marks)

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b) Determine the molecular formula of the compound (1 mark)

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7. A mixture contains ammonium chloride, copper (ii) oxide and sodium chloride. Describe how

each of the substances can be obtained from the mixture (3 marks)

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8. The electronic structures for elements represented by letters A, B, C and D are

A 2.8.6; B 2.8.2; C2.8.1; D 2.8.8;

a) Select the element which forms

i) A double charged cation

(½ mark)

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ii) A soluble carbonate (½ mark)

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b) Which element has the shortest atomic radius

(1 mark)

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9. a) State the Charles’ law (1 mark)

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b) A certain mass of a gas occupies 146dm3 at 291K and 98.31kpa. What would be its temperature if

its volume is reduced to 133dm3 at 101.325kpa. (2 marks)

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10. Painting, oiling, galvanizing and tin plating are methods of preventing rusting.

a) Explain the similarity of these methods in the way they prevent rusting (1 mark)

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b) Explain why galvanized iron objects are better protected from rusting even when scratched

(1 mark)

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11. The set up below was used to prepare a gas P.

a) Name gas P (1 mark)

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b) Write the equation for the reaction that takes place in the round bottomed flask

(1mark)

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c) Explain why gas P is collected over warm water (1 mark)

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12. Hydrogen gas is used in the laboratory to reduce copper (II) oxide. Name any other two gases

which can be used in the place of hydrogen gas (2 mark)

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Ammonium

Nitrate

Heat

Gas P

Warm

water

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13. Describe how a pure sample of lead (ii) Sulphate can be prepared in the laboratory starting

with lead metal (3

marks)

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14. Give the systematic names of the following organic compounds.

a) i)

H3C H

C C (½ Mark)

H CH3

ii) CH3(CH2)4 CH3 (½ Mark)

b) Describe a simple chemical test which can be used to distinguish the following organic

compounds

C4H8 and C5H12 (2 marks)

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15. When the chlorides of Aluminium and silicon are dissolved in water, the resulting solution

has a Ph of 3.0. Explain (2marks)

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16. 0.84g of Aluminium reacted completely with chlorine gas. Calculate the volume of chloride

gas used (molar gas volume is 24dm3, Al = 27) (3 marks)

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17. Graphite is one of the allotropes of carbon

a) Name one other element that exhibits allotrophy (1 mark)

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b) Explain why graphite is used as a lubricant (2 marks)

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………

18. Study the flow diagram below and answer the questions that follow

a) Name the reagent used in step 1 (1 mark)

………………………………………………………………………………………………………

………………………………………………………………………………………………………

………………

b) Name the catalyst used in step II

(1mark)

H2

Step II Step 1

CH3CH2

OH

CH2 =

CH2 X

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Step I

L

Step II

………………………………………………………………………………………………………

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c) Name x (1mark)

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19. The simplified flow chart shows some steps in the manufacture of sodium carbonate by

Solvay process.

a) Identify substance L (1 mark)

………………………………………………………………………………………………………

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b) Name the process taking place in step II (1 mark)

………………………………………………………………………………………………………

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c) Name one use of sodium carbonate (1 mark)

Step III

Sodium

hydrogen

Carbonate

Ammonium

Chloride

Brine

Carbon (IV)

Oxide

Sodium

Carbonate

Ammonium

chloride and

sodium

hydrogen

Carbonate

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………………………………………………………………………………………………………

………………………………………………………………………………………………………

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20. Under certain conditions, chlorine gas reacts with sodium hydroxide to form sodium

hypochlorite.

a) Name the conditions under which sodium hydroxide reacts with chlorine to form sodium

hypochlorite (2 mark)

………………………………………………………………………………………………………

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b) State one use of sodium hypochlorite (1mark)

………………………………………………………………………………………………………

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21. Write down the property of concentrated sulphiric (vi) acid which is shown by the reactions

below (3 mark)

a) CH3CH2OH(l) CH2 = CH2(g) + H2O (l)

………………………………………………………………………………………………………

………………………………………………………………………………………………………

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b) NaCl(s) + H2SO4(l) NaHSO4(aq)+HCl(g)

………………………………………………………………………………………………………

………………………………………………………………………………………………………

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c) CU(s) + 2H2SO4(l) CUSO4(aq) + SO2(g) + 2H2O(l)

………………………………………………………………………………………………………

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22. Write equations to show the effect of heat on each of the following.

a) Ammonium nitrate (1 mark)

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………………………………………………………………………………………………………

………………………………………………………………………………………………………

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b) Lead (II) carbonate (1 mark)

………………………………………………………………………………………………………

………

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………

c) Sodium hydrogen carbonate (1 mark)

………………………………………………………………………………………………………

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23. The apparatus below was set up to show the catalytic oxidation of ammonia. Study the

diagram and answer the questions that follow;

a) Write an equation for the reaction that takes place in the gas jar (1 mark)

………………………………………………………………………………………………………

………………………………………………………………………………………………………

………………

b) Why is it necessary to have a hot platinum wire in the gas jar (1mark)

………………………………………………………………………………………………………

………………………………………………………………………………………………………

………………

c) After sometime brown fumes are observed in the gas jar. Explain on the observation.

(1 mark)

Hot platinum wire

Gas

jar

Dry

NH3

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………………………………………………………………………………………………………

………………………………………………………………………………………………………

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24. 20.0cm3 of a solution containing 4g per litre of sodium hydroxide was neutralized by 8.0cm3

of dilute sulphiric (VI) acid. Calculate the concentration of sulphiric (VI) acid in moles per litre

Na=23, 0=16 H=1 s=32 (3 marks)

………………………………………………………………………………………………………

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………………

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25. Draw and name the structural formula of the compound formed when one mole of ethyne

reacts with one mole of chlorine gas (2 mark)

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26. The diagram below shows an incomplete set up for the laboratory preparation and collection

of sulphur (IV) oxide gas. Study it and answer the questions that follow.

a) Complete the set up to show how dry sulphur (IV) oxide gas may be collected

(2 mark)

b) Name

Liquid A

Heat

Solid B

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i) Liquid A (½ mark)

……………………………………………………………………………………

…………………………

ii) Solid B (½ mark)

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27. a) i) State the Gay Lussac’s law (1 mark)

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ii) 10cm3 of a gaseous hydrocarbon, C2Hx required 30cm3 of oxygen for complete

combustion. If

steam and 20cm3 of carbon (IV) oxide were produced, what is the value of X (2 marks)

………………………………………………………………………………………………………

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28. In an experiment a test tube full of chlorine water was inverted in chlorine water as shown in

the diagram below and then the set up left in the sunlight for one day.

After one day, a gas was found to have collected in the test tube

Chlorine water

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a) Identify the gas (1 mark)

………………………………………………………………………………………………………

………………………………………………………………………………………………………

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b) What will happen to the pH of the solution in the beaker after one day? Give a reason(2 mark)

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29. When a solid sample of sulphur is heated in a testtube, it changes into a liquid which flows

easily; on further heating the liquid darkens and does not flow easily. Explain these observations.

(2 mark)

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30. State and explain what would happen if a dry paper was dropped in a gas jar full of chlorine

(2 mark)

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KCSE MOCK 6

233/2

CHEMISTRY

Paper 2

(THEORY)

TIME 2 HOURS

1. The grid is part of the periodic table. The letters are not the actual symbols of the element. Use

the information to answer the questions that follow.

P Y

K Q T

W

R S

a) Which one is the most reactive

i) Metal? Explain (1½ marks)

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ii) Non- metal? Explain (1½ marks)

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b) Name the family to which K belongs

(1mark)

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…

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c) Identify a monoatomic element (1 mark)

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d) Write the formula of the compound formed when Q and W react (1 mark)

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e) Compare the atomic radius of K and T (2 marks)

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f) The mass number of J is 31, its number of neutrons is 16. Place J in periodic table above

(1mark)

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g) Element K reacts with water at room temperature to produce 0.2 dm3 of gas.

Determine the mass of K which reacted with water (molar gas volume at

RTP = 24 dm3; R.A.M of K = 12) Use the equation below

(2marks)

K(s) + 2H2O K(OH)2(cos) + H2(g)

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h) Use dots(.) and crosses (x) to represent the outermost electrons and show the bonding in the

compound formed between K and T. (2marks)

……………………………………………………………………………………

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2. (a) Study the set-up below and answer the questions that follow

i) State the property of hydrogen being investigated by passing the gas over heated copper (II)

oxide. (1mark)

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…………………………………

ii) State two observations made in the combustion tube (2 marks)

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…………………………………

iii) Write a balanced equation for the reaction that occurs when hydrogen burns at point x

(1mark)

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…………………………………

(b) In the laboratory preparation of hydrogen, zinc metal is reacted with

dilute hydrochloric acid to

generate hydrogen. State the reason why no hydrogen gas would be generated

if;

i) dilute nitric (v) acid is used in place of dilute hydrochloric acid (1

mark)

Dry hydrogen

x

Heat

Copper (II) oxide

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……………………………………………………………………………………

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…………………………………………

ii) copper metal is used in place of zinc metal (1 mark)

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c) Give the main reason why helium has replaced hydrogen in filling

observation balloons. (1mark)

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d) Give a reason why phosphorous is stored in water (1 mark)

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…………………………………………

e) Draw a dot (.) and cross (x) diagram to illustrate bonding in a water molecule

(1 mark)

f) Describe one chemical test and one physical test for water

i) chemical test (1 mark)

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ii) physical test (1 mark)

……………………………………………………………………………………

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…………………………………………

3. The diagram below represents a set up that was used to isolate dry nitrogen from the air. Study it

and answer the questions that follow.

Name liquid A and B (2marks)

i) A

………………………………………………………………………………………………………

………………………………………………………………………………………………………

………………

ii) B

………………………………………………………………………………………………………

………………………………………………………………………………………………………

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b) Identify one mistake in the apparatus set up (1 mark)

………………………………………………………………………………………………………

………………………………………………………………………………………………………

………………

c) State the purpose of

i) Aspirator

……………………………………………………………………………………

………………………………………………………………………………………………………

…………………………………

Tap

water

Air aspirator Liquid B

Gas syringe

Gas D

Heat

Copper turnings

Liquid A

Air Q P

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ii) liquid A

……………………………………………………………………………………

………………………………………………………………………………………………………

…………………………………

iii) liquid B

……………………………………………………………………………………

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iv) copper turnings

……………………………………………………………………………………

………………………………………………………………………………………………………

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d) Write an equation for the reaction taking place in the combustion tube. (1 mark)

………………………………………………………………………………………………………

………………………………………………………………………………………………………

………………

e) The gas D in the syringe was emptied into a gas jar when a burning magnesium was lowered into

the gas jar, a white solid was formed.

i) Name the white solid (1 mark)

……………………………………………………………………………………

………………………………………………………………………………………………………

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…………………………………………

ii) Write chemical equation for the formation of the white solid (1 mark)

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f) State the test for the following gases

i) Ammonia gas (1 mark)

……………………………………………………………………………………

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………………………………………………………………………………………………………

…………………………………………

ii) Nitrogen (II) oxide (1 mark)

……………………………………………………………………………………

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4. Below is a structure of a molecule of one hydrocarbon

H H H H H H

| | | | | |

H C C C C C C H

| | | | | |

H H H H H H

i) What is the molecular formula of this molecule (1 mark)

……………………………………………………………………………………

………………………………………………………………………………………………………

…………………………………

ii) To what homologous series doe the molecule belong (1 mark)

……………………………………………………………………………………

………………………………………………………………………………………………………

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iii) The formula of another hydrocarbon is C4H10. Write a balanced equation for the compete

combustion of this molecule.

(1 mark)

……………………………………………………………………………………

………………………………………………………………………………………………………

…………………………………

iv) The molecule below is ethane

H H

| |

C C

| |

H H

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Process Q

b. i) Give a reason why the molecule above is described as unsaturated. (1 mark)

……………………………………………………………………………………

………………………………………………………………………………………………………

…………………………………

ii) State the observation made when bromine water is shaken with ethane. (1 mark)

……………………………………………………………………………………

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c. Study the flow chart below and answer the question that follow. (1 mark)

a) Identify the processes (2marks)

i) P

……………………………………………………………………………………

………………………………………………………………………………………………………

…………………………………

ii) Q

……………………………………………………………………………………

………………………………………………………………………………………………………

…………………………………

b) Identify substances

(2marks)

i) Catalyst S

……………………………………………………………………………………

………………………………………………………………………………………………………

…………………………………

Catalyst S Cl2

H H

| |

C C n

| |

H H

Ethen

e

Ethano

l

M Ethane

Process P H2 (g)

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ii) M

……………………………………………………………………………………

………………………………………………………………………………………………………

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iii) Name the type of reaction which forms substances M (1 mark)

……………………………………………………………………………………

………………………………………………………………………………………………………

…………………………………

5. a) Below is a scheme of reaction sequence starting with sodium chloride. Study it and answer the


i) Identify substances (4 mark)

A C

……………………………………………

………………………………………………

B D

……………………………………………

………………………………………………

Step 2 Iron

D Step I

MnO2

Step 3

Sodium chloride

Hydrochloric

Acid

Chlorine

A

C

Step 5

Sodium

Chlorate (i)

B

Step 4

Iron

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ii) Write a balanced equation for the reaction represented by step 4.

(1 mark)

……………………………………………………………………………………

………………………………………………………………………………………………………

…………………………………

iii) State the role of manganese (iv) oxide in step 3 (1 mark)

……………………………………………………………………………………

………………………………………………………………………………………………………

…………………………………

b) Briefly described how a mixture of iodine, sodium chloride and lead (ii) Sulphate could be

separated (3 marks)

……………………………………………………………………………………

………………………………………………………………………………………………………

…………………………………

c) The set up below as used to investigate the effect of sunlight on chlorine water

State two observations made after two hours. (2 marks)

……………………………………………………………………………………

………………………………………………………………………………………………………

…………………………………

Sunlight

Basin

Chlorine water

Gas jar

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6. The table below gives some properties of three salts D, E and F.

S

Salt

D E F

S

Solubilit

y

I

Insoluble

S

Soluble

S

Soluble

E

ffect of

heat

D

ecomposes

forming

white

residue G

and

colourless

gas H. Gas

H forms a

white

precipitate

with lime

water.

D

ecomposes

to form a

yellow

residue

and two

gases B

and J .Gas

B is red

brown ,

gas J is

colourless.

D

issociates

into two

gases

KandL.

Gas K

turns

moist red

litmus

paper

blue. Gas

K and L

readily

recombin

es to

form

dense

white

fumes of

salt F

Further tests showed that when residue G was reacted with water and the

product heated with salt F; Gas K was evolved. When D reacted with Nitric (V) acid, there was

an effervesce. The resulting solution formed a white precipitate with dilute Sulphuric (VI) acid,

but not with hydrochloric acid

a) i) Identify

i) Gas H (½ mark)

……………………………………………………………………………………

………………………………………………………………………………………………………

…………………………………

ii) Gas B (½ mark)

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……………………………………………………………………………………

………………………………………………………………………………………………………

…………………………………

iii) Salt D (½ mark)

……………………………………………………………………………………

………………………………………………………………………………………………………

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iv) Salt F (½ mark)

……………………………………………………………………………………

………………………………………………………………………………………………………

…………………………………

ii) Write an equation for the thermal decomposition of salt D.

(1 mark)

……………………………………………………………………………………

………………………………………………………………………………………………………

…………………………………

iii) Name the compound formed when residue G is reacted with water.

(1 mark)

……………………………………………………………………………………

………………………………………………………………………………………………………

…………………………………

iv) A solution of salt E reacted with an aqueous solution of gas L forming a

white precipitate that

dissolved when warmed.

a) Write an ionic equation for the formation of the white precipitate (1 mark)

……………………………………………………………………………………

………………………………………………………………………………………………………

…………………………………

b) Write formulae of the ions that are present in salt E (1 mark)

……………………………………………………………………………………

………………………………………………………………………………………………………

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v) Explain what would be observed if sodium hydroxide solution was

added to a solution of E dropwise till in excess

(1 mark)

……………………………………………………………………………………

………………………………………………………………………………………………………

…………………………………

b) In preparation of Magnesium Carbonate Magnesium was burnt in air and the product collected.

Dilute hydrochloric acid was then added and the mixture filtered. Sodium carbonate was added to

the filtrate and contents filtered. The residue was washed and dried to give a white powder.

i) Name the product X (1 mark)

……………………………………………………………………………………

………………………………………………………………………………………………………

…………………………………

ii) Write a chemical equation for the formation of the product X. (1 mark)

……………………………………………………………………………………

………………………………………………………………………………………………………

…………………………………

iii) Name the filtrate collected after sodium carbonate was added. (1 mark)

……………………………………………………………………………………

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7. a) Study the set up below and answer the questions that follow.

i) State the role of concentrated Sulphuric (VI) acid in this reaction (1 mark)

Concentrated

Sulphuric (VI) acid

Carbon Acidified potassium

dichromate (VI)

Lime water

A B

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……………………………………………………………………………………

………………………………………………………………………………………………………

…………………………………

ii) State the observation made in boiling tube (2 marks)

A

……………………………………………………………………………………

………………………………………………………………………………………………………

…………………………………

B

……………………………………………………………………………………

………………………………………………………………………………………………………

…………………………………

b) When concentrated Sulphuric (VI) acid is added to sugar a black solid is formed. State the

property of concentrated Sulphuric (VI) acid demonstrated by the reaction.

(1 mark)

……………………………………………………………………………………

………………………………………………………………………………………………………

…………………………………

c) Sulphur (IV) oxide gas was bubbled in water then a few drops of barium chloride were added

immediately.

i) State the observation that was made. (1 mark)

……………………………………………………………………………………

………………………………………………………………………………………………………

…………………………………

ii) Write an ionic equation for the reaction that occurred on addiction of barium chloride (1 mark)

……………………………………………………………………………………

………………………………………………………………………………………………………

…………………………………

d) i) State the reason why sulphur (IV) oxide and air are passed through cleaners in the contact

process.

(1 mark)

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……………………………………………………………………………………

………………………………………………………………………………………………………

…………………………………

ii) State one catalyst used in the manufacture of Sulphuric (VI) acid (1 mark)

……………………………………………………………………………………

………………………………………………………………………………………………………

…………………………………

e) Define the term allotropy (1 mark)

……………………………………………………………………………………

………………………………………………………………………………………………………

…………………………………

f) State the test for hydrogen Sulphide (1 mark)

……………………………………………………………………………………

………………………………………………………………………………………………………

…………………………………

g) A concentrated Sulphuric (VI) acid has a concentration of 18.2m. Determine the volume of

the concentrated acid that would be mixed with distilled water to make one litre of 2m Sulphuric

(VI) acid.

……………………………………………………………………………………

………………………………………………………………………………………………………

…………………………………

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KCSE MOCK 7

Form 4

Chemistry Paper 1

Time: 2 Hours

1. The diagram below shows parts of a Bunsen burner.

A

B

C

a) Name the parts labelled (½ mark)

A

.......................................................................................................................................

B

.......................................................................................................................................

b) Give one use of the part labelled B (1 mark)

...........................................................................................................................................

.........

2. Hydrated copper (II) sulphate exists as blue crystals while anhydrous copper (II)

sulphate is a white powder. Describe a laboratory experiment that can be used to show that

the action of heat on hydrated copper (II) sulphate is a reversible reaction (2

marks)

...........................................................................................................................................

.........

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3. A piece of burning magnesium ribbon was placed in a gaSs jar full of Nitrogen gas.

The product Q formed was then reacted with water.

a) Write the chemical formula for the product Q (1 mark)

...........................................................................................................................................

.........

...........................................................................................................................................

.........

b) Write the equation for the reaction between product Q and wate (1 mark)

...........................................................................................................................................

.........

...........................................................................................................................................

.........

c) Using dot (•) and cross (x) diagrams to represent electrons, draw the structure

to show bonding in nitrogen molecule (1 mark)

1. (i) What are isotopes (1 mark)

................................................................................................................................................

....

................................................................................................................................................

(ii) Element Y (not the actual symbol of the element) has two isotopes with mass number

6 and 7. If the relative atomic mass of Y is 6.94, determine the percentage abundance

of each isotope (2 marks)

...........................................................................................................................................

.........

...........................................................................................................................................

.........

2. Given zinc oxide, dilute nitric (V) acid and sodium carbonate solution. Briefly describe

how you can prepare zinc carbonate (3 marks)

...........................................................................................................................................

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...........................................................................................................................................

.........

3. The elements shown in the table below (not actual symbols) belong to a certain family of

metals in the periodic table. Study the information and answer the questions that follow.

Element Atomic size (nm)

S 0.160

T 0.180

V 0.930

(i) Define the term ionization energy (1 mark)

...........................................................................................................................................

.........

...........................................................................................................................................

.........

(ii) Which element is likely to have the highest ionization energy. Explain(2

marks)

...........................................................................................................................................

.........

...........................................................................................................................................

.........

4. A certain mass of copper (II) carbonate was strongly heated.

a) Write a balanced chemical equation for the reaction (1 mark)

...........................................................................................................................................

.........

...........................................................................................................................................

.........

b) Given that 300cm3 of carbon(IV) oxide gas was collected at s.t.p. and this represents

83% yield, determine the mass of copper (II) carbonate heated. (molar gas volume =

22.4dm3, Cu=64, 0=16, C=12)

(3 marks)

...........................................................................................................................................

.........

...........................................................................................................................................

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...........................................................................................................................................

.........

5. (i) Give the IUPAC names for the following organic compounds

CH3 H H

I I

a) H – C – C – C = C – C – H

(1 mark)

I I

CH3 H H

...........................................................................................................................................

.........

...........................................................................................................................................

.........

O

II

b) CH3 CH2CH2 C – OH (1 mark)

...........................................................................................................................................

.........

...........................................................................................................................................

.........

O

II

c) CH3 CH2 C - O - CH2- CH2- CH3 (1 mark)

...........................................................................................................................................

.........

...........................................................................................................................................

.........

(ii) A polymer has the following structure

CH3 H CH3 H

I I I I

- C - C - C - C

I I I I

H H H H n

A sample of this polymer is found to have a molecular mass of 2184. Determine

the number of monomers of the polymer. (C = 12, H = 1) (3

marks)

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...........................................................................................................................................

.........

...........................................................................................................................................

.........

...........................................................................................................................................

.........

6. During an experiment, chlorine was bubbled into a solution of sodium bromide in a

beaker

a) State and explain one observation made (2 marks)

...........................................................................................................................................

.........

...........................................................................................................................................

.........

b) Write an ionic equation for the reaction that took place in the beaker (1 mark)

...........................................................................................................................................

.........

...........................................................................................................................................

.........

7. Hardness of water may be removed by either boiling or addition of chemicals.

a) Write down an equation to show how boiling removes hardness of water (1 mark)

...........................................................................................................................................

.........

...........................................................................................................................................

.........

b) Name two chemicals that are used to remove hardness of water (2 marks)

...........................................................................................................................................

.........

...........................................................................................................................................

.........

8. i) Define solubility (1 mark)

...........................................................................................................................................

.........

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...........................................................................................................................................

.........

ii) 115g of a saturated solution at 65°C is found to contain 65g of potassium nitrate.

Calculate the solubility of potassium nitrate at 65°C. (2 marks)

...........................................................................................................................................

.........

...........................................................................................................................................

.........

9. The equation for the reversible reaction of Bismuth (III) chloride in water is

BiCl3(s) + H2O(l) BiOCl(s) + 2H+(aq) + 2Cl-

(aq)

a) State Le chatelier’s principle (1 mark)

...........................................................................................................................................

.........

...........................................................................................................................................

.........

b) What would be the effect of adding NaOH pellets to the equilibrium mixture. Explain.

(2 marks)

...........................................................................................................................................

.........

...........................................................................................................................................

.........

10. In the equation, below identify the reagent that acts as an acid in the forward reaction.

Give a reason.

NH+4(aq) + H2O(l) NH3(aq) + H3O+

(aq) (2 marks)

...........................................................................................................................................

.........

...........................................................................................................................................

.........

11. In preparation of oxygen gas, a student used hydrogen peroxide and added a black solid

and collected the gas over water.

a) What is the name of the black solid and what is its function (1 mark)

...........................................................................................................................................

.........

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...........................................................................................................................................

.........

b) During collection of the gas,why should the first bubbles be allowed to escape(1 mark)

...........................................................................................................................................

.........

...........................................................................................................................................

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c) Give one main advantage of collecting a gas over water. (1 mark)

...........................................................................................................................................

.........

...........................................................................................................................................

12. Explain the following observation, a one molar solution of nitric (III) acid (1M HNO2)

has a pH of 2 where as a one molar solution of chloric(I) acid (IM HOCl) pH of 4.

(2 marks)

...........................................................................................................................................

.........

...........................................................................................................................................

.........

13. a) Study the set-up below and use it to answer the questions that follow.

concsulphuric acid hot zinc oxide carbon

(11)

oxide

flame

tube M

Conc sodium hydroxide solution

substance

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R

a) Identify substance R (1 mark)

...........................................................................................................................................

.........

...........................................................................................................................................

.........

b) State the function of concentrated sodium hydroxide solution (1 mark)

...........................................................................................................................................

.........

...........................................................................................................................................

.........

c) State the property of carbon (II) oxide gas demonstrated in the above set-up(1

mark)

...........................................................................................................................................

.........

...........................................................................................................................................

.........

d) Write a balanced chemical equation for the reaction occurring in tube M.(1 mark)

...........................................................................................................................................

.........

...........................................................................................................................................

.........

14. 200cm3 of oxygen diffused through a porous plug in 60 seconds. How long will it take

300cm3 of sulphur (IV) oxide to diffuse through the same plug? (S = 32, O = 16)

(3 marks)

...........................................................................................................................................

.........

...........................................................................................................................................

.........

...........................................................................................................................................

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15. Study the diagram below and answer the questions.

Combustion tube flame

dry gas y

lead (11)oxide heat blue cobalt chloride crystals

(i) Identify gas Y (1 mark)

...........................................................................................................................................

State and explain two observations made in the combustion tube. (2 mark)

...........................................................................................................................................

.........

...........................................................................................................................................

.........

(ii) Write a chemical equation for the reaction between lead (II) oxide and gas (1 mark)

...........................................................................................................................................

.........

..........................................................................................................................................

16. i) State Hess’s law. (1 mark)

...........................................................................................................................................

.........

...........................................................................................................................................

(ii) The figure below shows an energy cycle diagram.

ΔH1 = -187.8kjmol-1

ΔH2 = -285.8kjmol-1

ΔH3

H2(g) +

O2(g) H2O2(l)

H2O(l) +

½O2(g)

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a) Give the name of the enthalpy change ΔH1 (1 mark)

...........................................................................................................................................

.........

...........................................................................................................................................

.........

b) Determine the value of ΔH3 (1 mark)

...........................................................................................................................................

.........

...........................................................................................................................................

.........

17. The table below shows the pH values of some solutions.

Solutions A B C D

pH values 13.0 7.0 2.0 6.5

a) Which solution reacts vigorously with magnesium metal? Explain. (1 mark)

...........................................................................................................................................

.........

...........................................................................................................................................

.........

b) Which solution is likely to be that of lemon juice? (1 mark)

...........................................................................................................................................

.........

...........................................................................................................................................

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c) Which solution is likely to produce green colour with the universal indicator.(1

mark)

...........................................................................................................................................

.........

...........................................................................................................................................

.........

18. The diagram below shows a set-up that was used to prepare and collect a sample of nitric

(V) acid in the laboratory.

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concentrated

sulphuric(v1) acid

solid

Potassium cold water

nitrate

heat

a) Give a reason why it is possible to separate nitric acid from the sulphuric (VI) acid in

the set-up (1 mark)

...........................................................................................................................................

.........

...........................................................................................................................................

.........

b) Name another substance that can be used instead of potassium nitrate (1 mark)

...........................................................................................................................................

.........

...........................................................................................................................................

.........

c) Give one use of nitric (V) acid (1 mark)

...........................................................................................................................................

.........

...........................................................................................................................................

.........

19. The flow chart below shows some processes involved in the industrial extraction of zinc

metal.

Air

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Ore

Coke Gases

a) Name one ore from which Zinc is extracted (1 mark)

...........................................................................................................................................

.........

...........................................................................................................................................

.........

b) Write the equation of the reaction taking place in unit II (1 mark)

...........................................................................................................................................

.........

...........................................................................................................................................

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c) Name two uses of Zinc metal (1 mark)

...........................................................................................................................................

.........

...........................................................................................................................................

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20. Thorium undergoes two consecutive alpha decays followed by two consecutive

beta decays to form the nuclide . Identify the values of and . (2 marks)

...........................................................................................................................................

.........

...........................................................................................................................................

.........

21. Below is part of the flow diagram of the contact process

Liquid P

Unit

I SO

2

Unit II

Zinc

metal

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SO3Liquid N

Conc Sulphuric (VI) acid

a) Identify

(i) Liquid P (1 mark)

...........................................................................................................................................

.........

(ii) Liquid N (1 mark)

...........................................................................................................................................

.........

b) Write the equation for the reaction taking place in chamber R (1 mark)

...........................................................................................................................................

.........

...........................................................................................................................................

.........

22. a) Define the term oxidation state (1 mark)

...........................................................................................................................................

.........

...........................................................................................................................................

.........

b) Calculate the oxidation states of manganese and chromium in:

(i) MnO2 (1 mark)

...........................................................................................................................................

.........

...........................................................................................................................................

.........

(ii) CrO-4 (1 mark

Chamber

Q

Chamber

R

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...........................................................................................................................................

.........

...........................................................................................................................................

.........

23. When hydrogen sulphide gas is bubbled through a solution of iron (III) chlorides, a green

solution and a yellow solid are formed. Explain the observations (2 marks)

...........................................................................................................................................

.........

...........................................................................................................................................

.........

...........................................................................................................................................

.........

...........................................................................................................................................

.........

24. During purification of copper by Electrolysis, 1.48g of copper were deposited when a

current was passed through copper (II) sulphate solution for 2½ hours. Calculate the

amount of current that was passed

(3 marks)

(Cu = 63.5, IF = 96500C)

KCSE MOCK 7

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233/2

CHEMISTRY

Paper 2

Time: 2 hours

1. A. In an experiment to determine the percentage of oxygen in air, the apparatus below

were set up. Study the set up and the information provided to answer the


A 500cm3 measuring cylinder K was filled with water and assembled for gas collection.

Copper turnings were heated red hot and water was slowly passed into 500cm3 flask H

until it reached the 500cm3 mark. A colourless gas was collected in K.

(i) What was the purpose of passing water into flask H? (1 mark)

…………………………………………………………………………………………………

…………………………

(ii) What observations were made in the tube I? (1 mark)

…………………………………………………………………………………………………

…………………………

(iii) Name one of the gases that is likely to be found in J. (1 mark)

Copper turnings

Heat

Water

I

K

Flask H (500cm3)

J 100 200 300 400 500

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…………………………………………………………………………………………………

…………………………

(iv) What was the volume of the gas collected in the measuring cylinder at the end of

the experiment? (1 mark)

…………………………………………………………………………………………………

…………………………

(v) Calculate the percentage of oxygen in air using the above results. (2 marks)

B. Study the diagram below and answer the questions that follow.

(a) Give one observation made in the combustion tube after some time. (1 mark)

…………………………………………………………………………………………

…………………………………

(b) Write an equation for the formation of the colourless liquid Y. (1 mark)

…………………………………………………………………………………………………

…………………………

(c) What was the aim of the above experiment as demonstrated in the combustion

tube? Explain. (2 marks)

…………………………………………………………………………………………

…………………………………………………………………………………………

Colourless liquid Y

Copper (II) oxide Ice cold water

Heat

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…………………………………………………………………………………………

…………………………………………………………………………………………

……………

2. Use the information below to answer the questions that follow. The letters are not the

actual symbols of the elements.

Element Atomic No. M.P0C B.P0C Ionic radius (nm)

P 11 98 890 0.095

Q 12 650 1110 0.065

R 13 660 2470 0.050

S 14 1410 2360 0.041

T 15 44.2 & 590 280 0.034

U 16 113 & 119 445 0.184

V 17 -101 -35 0.181

W 18 -189 -186 -

(a) (i) Write the electronic configuration of the atoms represented by letters T

and W. (1 mark)

(ii) State the nature of the oxides of the elements represented by Q and U.

(2 marks)

…………………………………………………………………………………………………

…………….

…………………………………………………………………………………………………

…………….

(b) Why does the elements represented by the letters T and U have two values of

melting points? (1 mark)

…………………………………………………………………………………………………

…………………………

(c) Explain the following observations in terms of structure and bonding.

(i) There is an increase in boiling point from P to R. (2 marks)

…………………………………………………………………………………………

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…………………………………………………………………………………………

…………………………………………………………………………………………

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………………………………………………

(ii) Element S has a high boiling point. (2 marks)

…………………………………………………………………………………………

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(iii) There is a decrease in boiling points from U to W. (2 marks)

…………………………………………………………………………………………

…………………………………………………………………………………………

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(d) (i) Compare the atomic radius of U and V. (1 mark)

…………………………………………………………………………………………………

…………………………

…………………………………………………………………………………………………

…………………………

……………………………………………………………………………………………………………………………

……………………………………………………………………………………………………………………………

(ii) Why is there no ionic radius for W reported in the table? (1 mark)

……………………………………………………………………………………………………………………………

……………………………………………………………………………………………………………………………

3. (a) The solubilities of potassium nitrate and potassium bromide at different temperatures was determined. The following data was obtained.

Temperature 0C 0 10 20 30 40 50 60 70 80

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(ii) What was the solubility of each salt at 650C? (1 mark)

(iii) 100g of a saturated solution of potassium nitrate at 700C was cooled to

200C. What mass of the crystals will be crystallized? (2 marks)

(b) Study the flow chart below and answer the questions that follow.

(i) Write an equation for the formation of solid A and gas B. (1 mark)

…………………………………………………………………………………………………

…………………………

(ii) Name;

Metal

carbonate

Heat Solid A

+

Gas B

Dil. HCl Solution

C

Deep blue

solution E Solid D

A few drops of

NH3(aq)

Excess of

NH3(aq)

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Solution C - …………………………………………………..

(1 mark)

Solid D - …………………………………………………..

(1 mark)

(c) Write the formula of the complex ion in solution E. (1 mark)

…………………………………………………………………………………………………

…………………………


(a) Name substance. (3 marks)

X - ………………………………………………………………….

Q - ………………………………………………………………….

R - ………………………………………………………………….

(b) Write down an equation for the reaction represented by step III. (1 mark)

W

Q

R

H H

C C

H H

III

NaOH

Heat

II

X Z

n

Y

HI

VI

Na

NaOH

I

NaOH

V

IV

Na2CO3

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…………………………………………………………………………………………………

…………………………

(c) What are the conditions and reagent required for steps?

(i) I (2 marks)

Reagent -

…………………………………………………………………………

………..

Condition -

…………………………………………………………………………

………..

(ii) IV (2 marks)

Reagent -

…………………………………………………………………………

………..

Condition -

…………………………………………………………………………

………..

(b) Name the process represented by: (4 marks)

I - ……………………………………………………………………….

II - ……………………………………………………………………….

IV - ……………………………………………………………………….

V - ……………………………………………………………………….

5. I. Study the scheme below and answer the questions that follow.

Substance A Substance B

Ammonia gas Colourless

gas D Brown gas

Step I

Water

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(a) Identify substances. (3 marks)

A - …………………………………………………………………..

B - …………………………………………………………………..

D - …………………………………………………………………..

(b) State the catalyst necessary for; (2 marks)

Step I -

…………………………………………………………………………………………

Step II -

…………………………………………………………………………………………

(c) Write an equation for the reaction taking place in step II. (1 mark)

…………………………………………………………………………………………………

……………………….

(d) Write two balanced chemical equations for the reaction between chlorine

gas and;

(i) Hot and concentrated sodium hydroxide. (1 mark)

…………………………………………………………………………………………………

……………….

(ii) Dilute and cold sodium hydroxide. (1 mark)

…………………………………………………………………………………………………

………………

II. The diagram below shows an experiment in which the Lead (II) nitrate crystals are

heated.

Oxygen

Catalyst F

Step II

Oxygen

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(a) Name; (2 marks)

(i) Liquid P -

………………………………………………………………………..

(ii) Gas Y -

………………………………………………………………………..

(b) Write a balanced chemical equation for the decomposition of Lead (II) nitrate.

(1 mark) …………………………………………………………………………………………

………………………………

(c) Explain how you can distinguish between nitrogen (II) oxide and nitrogen (I) oxide.

(2 marks)

…………………………………………………………………………………………………

…………………………………………………………………………………………………

…………………………………………………………………………………………………

…………………………………………………………………………………………………

……………

…………………………………………………………………………………………………

……………………………………

6. I. Study the standard electrode potentials given below and answer the questions that

follow.

Gas Y

Liquid P

Ice

Powdered Pb(NO3)2

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(a) Identify the strongest:

(i) Reducing agent ……………………….. (1

mark)

(ii) Oxidizing agent ……………………….. (1

mark)

(b) Calculate the e.m.f of a cell made of G and M. (2 marks)

(c) Write the cell representation for the above cell in (b). (1 mark)

(d) Draw a cell diagram for the cell in (b) above. (2 marks)

(e) Write the cell reaction for the drawn cell diagram in (d) above. (1 mark)

II. Electrolysis of aqueous solution of metal M resulted in the deposition of 1.07g of

metal upon passage of a current of 1.32 amperes for 75 minutes.

(M = 52, 1F = 96500C)

(i) Calculate the quantity of electricity passed through the cell. (1 mark)

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(ii) Calculate the charge on the metal ion. (3 marks)

7. Extraction of iron involves two main processes, smelting and refining. Below is the blast

furnace which is used to smelt iron from its ore.

(a) (i) What does the word smelt mean? (1 mark)

…………………………………………………………………………………………

………………………………….………………………………………………………

…………………………………………………………………….

(ii) Name the reducing agent in the process. (1 mark)

3000C 5000C 6000C 8000C 16000C

CO2, CO as waste

Carbon (IV) oxide recycled

Hot air blast from stove

Slag Iron Molten iron from tap

Slag tap

Fire brick lining

C

B

A

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…………………………………………………………………………………………………

(iii) What is the role of the hot air blast in the process? (2 marks)

…………………………………………………………………………………………

………………………………….

(b) Write equations for the reactions that take place at the region marked A, B and C.

(3 marks)

A -

…………………………………………………………………………………

…………………….

B -

…………………………………………………………………………………

…………………….

C -

…………………………………………………………………………………

…………………….

(c) What is the purpose of limestone in the extraction process? (1 mark)

…………………………………………………………………………………………

………………………………….

(f) Write equations to show how impurities are removed from the ore.

(3 marks)

…………………………………………………………………………………………

………………………………….………………………………………………………

…………………………………………………………………….……………………

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233/1

CHEMISTRY

Paper 1

(Theory)

Time 2 Hours

1. (a) What is the importance of the shape of a conical flask? (1 mark)

…………………………………………………………………………………………………...

………………………………………………………………………………………………………

2. A mixture consists of sulphur powder and iron filings.

(i) Describe how to obtain sulphur from the mixture using methylbenzene. (2 marks)

…………………………………………………………………………………………………

……………………………………………………………………………………………….

……………………………………………………………………………………………….

………………………………………………………………………………………………

(ii) Is the mixture homogeneous or heterogeneous? Explain. (1 mark)

……………………………………………………………………………………………

……………………………………………………………………………………………

……………………………………………………………………………………………..

3. Nitrogen gas can be prepared in the laboratory using a mixture of ammonium chloride solution and

sodium nitrite solution.

(a) The reaction occurs in two steps. State the two steps in the correct order. (2 marks)

……………………………………………………………………………………………………..

……………………………………………………………………………………………………..

……………………………………………………………………………………………………..

(b) State two uses of nitrogen. (1 mark)

……………………………………………………………………………………………………..

……………………………………………………………………………………………………..

4. (a) Draw structural formulae of two positional isomers with molecular formula C4H8.

(2 marks)

(b) Study the equation below and answer the questions that follow.

C6H14 + Cl2 C6H13Cl + HCl

(i) State the condition under which this reaction occurs. (1 mark)

………………………………………………………………………………………………

(ii) Give the general name of this type of reaction. (1 mark)

………………………………………………………………………………………………...

5. (a) Define hydration energy. (1 mark)

…………………………………………………………………………………………………...

…………………………………………………………………………………………………..

(b) Given that: the hydration energies of Ca2+ and Cl- are -1891 kJ mol-1 and -384 kJ mol-1

respectively, and that the lattice energy of calcium chloride is +2237 kJ mol-1.Calculate the

molar enthalpy change of solution of calcium chloride. (3 marks)

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6. The standard electrode potentials of a metal G and iron are given below.

Fe2+(aq) + 2e Fe(s) -0.44V

G2+(aq) + 2e G(s) -0.91V

A piece of iron is coated with metal G. If the coating is scratched, would the iron be protected

form rusting? Explain. (3 marks)

…………………………………………………………………………………………………………

…………………………………………………………………………………………………………

…………………………………………………………………………………………………………

………………………………………………………………………………………………7. (a)Why

is the percentage of carbon (IV) oxide in the atmosphere fairly constant? (1 mark)

………………………………………………………………………………………………..

………………………………………………………………………………………………..

(b) Calculate the volume of carbon(IV)oxide in 8,000 m3 of air contained in a hall.(2 marks)

8. State two conditions that would make the boiling point of water to be higher than 100oC.

(2 marks)

……………………………………………………………………………………………………..

………………………………………………………………………………………………………

9. Explain the effects of the accumulation of nitrogenous compounds in water masses? (2 marks)

………………………………………………………………………………………………………

………………………………………………………………………………………………………

………………………………………………………………………………………………………

10. Study the table below and use it to answer the questions that follow. (The letters do not represent

the actual symbols of the elements).

Element Q R S T U

Atomic

number

5 20 3 18 5

Atomic mass 10 40 7 40 11

(a) Select two letters that represent the same element? Give a reason. (2 marks)

……………………………………………………………………………………………

(b) Give the number of neutrons in an atom of element S. (1 mark)

……………………………………………………………………………………………

11. Dry carbon (II) oxide gas was passed over heated lead (II) oxide.

(a) Write an equation for the reaction. (1 mark)

……………………………………………………………………………………………

(b) Give one industrial application of the above reaction. (1 mark)

……………………………………………………………………………………………

(c) Name another gas that can be used in the above reaction. (1 mark)

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………………………………………………………………………………………………

12. (a) Proteins are obtained from amino acids monomers. Complete the equation below to show

the polymer formed. (1 mark)

H2NCH2COOH + H2NCHCH3COOH

(b) Name the type of polymerization shown above. (1 mark)

…………………………………………………………………………………………………

13. The set up below was used to prepare dry hydrogen gas. Study it and answer the questions

that follow.

(i) With a reason, identify the mistake in the set-up above. (1 mark)

…………………………………………………………………………………………………

…………………………………………………………………………………………………

…………………………………………………………………………………………………

(ii) What would be liquid Y? (1 mark)

…………………………………………………………………………………………………

…………………………………………………………………………………………………

(iii) Give two physical properties of hydrogen gas (1 mark)

…………………………………………………………………………………………………

…………………………………………………………………………………………………

14. Study the following equilibrium equation.

2X2(g) + Y2(g) 2X2Y(g) H = -197kJ/mol

(a) Suggest two ways of increasing the yield of X2Y. (1 mark)

…………………………………………………………………………………………………

…………………………………………………………………………………………………

(b) Draw the energy level diagram for the forward reaction. (2 marks)

Cardboar

d

Hydrochloric

acid

Zinc granules

Liquid Y

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15. 5.0g of calcium carbonate were allowed to react with 25cm3 of 1.0M hydrochloric acid until

there was no further reaction. Calculate the mass of calcium carbonate that remained unreacted.

(3 marks)

(Ca = 40, C = 12, O = 16)

…………………………………………………………………………………………………

………………………………………………………………………………………………………

……………………………………………………………………………………………

…………………………………………………………………………………………………

…………………………………………………………………………………………………

…………………………………………………………………………………………………

16. (a) State Graham’s law of diffusion. (1 mark)

……………………………………………………………………………………………….

………………………………………………………………………………………………..

……………………………………………………………………………………………….

(b) 50cm3 of Carbon (IV) Oxide diffuses through a porous plate in 15 seconds. Calculate the

time taken by 75cm3 of Nitrogen (IV) Oxide to diffuse through the same plate under similar

conditions. (C = 12, 0 = 16, N = 14) (2 marks)

17. A student fetched water from a river in a limestone area. He used it for washing and realized

that it did not lather easily.

(i) Name the two ions that prevent lathering. (1 mark)

………………………………………………………………………………………………

……….…………………………………………………………………………………

(ii) Given that the structure of soap is C17H35COONa.

Explain by means of ionic equations how the above ions prevent lathering. (2 marks)

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…………………………………………………………………………………………………..

…………….…………………………………………………………………………………….

…………………………………………………………………………………………………..

.…………….……………………………………………………………………………………

……………………………………………………………………………

18. A student burnt magnesium ribbon in a gas jar full of sulphur (IV) oxide gas.

(i) State two observations made in the gas jar. (2 marks)

………………………………………………………………………………………………………

……….……………………………………………………………………………………………

………………..............................................................................................................

(ii) Write an equation for the reaction that took place. (1 mark)

……………………………………………………………………………………………..

19. M grammes of a radioactive isotope decayed to 5 grammes in100 days. The half life of the

isotope is 25 days.

(a) What is meant by half life? (1 Mark)

………………………………………………………………………………………………………

……….……………………………………………………………………………………

(b) Calculate the initial mass M of the radioactive isotope. (2 Marks)

20. (i) With the aid of a well labeled diagram, show that the innermost region of a non luminous

flame consist of unburnt gas. (1½ marks)

(ii) Highlight the steps followed when lighting a Bunsen burner. (1½ marks)

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21. The diagram below shows an experiment involving chlorine water.

a)State and explain the observations made after 24 hours. (2 marks)

………………………………………………………………………………………………………

………………………………………………………………………………………………………

………………………………………………………………………………………………………

b)Write an equation to show the formation of gas A. (1mark)

…………………………………………………………………………………………....................

c)State one use of chlorine gas. (1mark)

............................................................................................................................................................

22. Study the reaction scheme below and the answer questions that follow.

Copper step Conc. nitric (v) solution +Gas C

1 acid B

Step II Fe(s)

pale green

solution.

(i) Identify: (2mark)

Solution B

…………………………………………………………………………………………………

Gas C

…………………………………………………………………………………………………

(ii) What type of reaction is taking place in step II (1mark)

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………………………………………………………………………………………………

23. a) Define solubility. (1 mark)

…………………………………………………………………………………………………………

……

…………………………………………………………………………………………………………

……

…………………………………………………………………………………………………………

…….

b) In an experiment to determine the solubility in water at 300c, the following results were

obtained.

Mass of empty evaporating dish = 26.2g

Mass of evaporating dish + saturated solution = 42.4g.

Mass of evaporating dish + dry solid Y = 30.4g

Use this data to calculate the solubility of Y at 300C . (3 marks)

…………………………………………………………………………………

………………………………………………………………………………………………………

…………………………………. ..

………………………………………………………………………………………………………

………………………………………………………………………………………………………

………………

…………………………………………………………………………………

………………………….

24. In terms of structure and bonding. Explain why water (H2O) is a liquid at room temperature while

Hydrogen sulphide (H2S) is a gas. (2 marks)

…………………………………………………………………………………………………………

…………………………………………………………………………………………………………

…………………………………………………………………………………………………………

……………..……………………………………………………………………………………………

…………………………………………………………………………………………………………

…………………………………………………………………………………………………………

……..

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25. Explain why hard water flowing in lead pipes may be safer for

drinking than soft water

flowing in the same pipes.

(2 marks)

…………………………………………………………………………

……………………………………………………………………………………………

……………………………………………………………………………………………

……………………………………………………………………………………………

……………………………………………………………

26. Air was passed through reagents as shown below.

i)State and explain the observations made when air is passed through chamber A for a long time.

(2 marks)

…………………………………………………………………………………………………………

…………………………………………………………………………………………………………

…………………………………………………………………………………………………………

…………………………………………………………………………………………………………

…………………………………………………………..

…………………………………………………………………………………………………………

……………………………………………………..

…………………………………………………………………………………………………………

…………………………………………………….

ii) Name one component in Explain

(1 mark)

…………………………………………………………………………………………………………

…………………………………………………….

Air Calcium hydroxide

solution

Hot

Copper

Excess hot

Magnesium C

A B

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27. Using dots (·) and crosses (x), draw the dimer structure of aluminium chloride and name the

bonds. (Al=13, Cl=17)

(2 marks)

28. Iron is extracted from its ore by the blast furnace process.

a) Name the chief ore from which iron is extracted from. (1 mark)

…………………………………………………………………………………………………………

……………………………………..

b) An ore is suspected to contain mainly iron. Describe a method that can be used to confirm

the

presence of iron in the ore.

(2 marks)

…………………………………………………………………………………………………………

……………………………………………

…………………………………………………………………………………………………………

……………………………………………

…………………………………………………………………………………………………………

…………………………………………….

…………………………………………………………………………………………………………

…………………………………………….

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233/2

CHEMISTRY

PAPER 2

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(THEORY)

TIME: 2 HOURS

1. The figure below represents a section of the periodic table. Study it and answer questions

(a) to (h). Note that the letters do not represent the actual symbols of the elements.

A D

B G J F H E

C I

(a) Consider elements D, H and I.

(i) Give the chemical family of these elements. (1 mk)

………………………………………………………………………………………………

(ii) How do their ionic size compare. (1 mk)

………………………………………………………………………………………………

………………………………………………………………………………………………

(iii) Compare and explain the reactivity of the three elements. (2 mks)

………………………………………………………………………………………………

………………………………………………………………………………………………

………………………………………………………………………………………………

(b) (i) Write the electronic configuration of:

Element H (1 mk)

………………………………………………………………………………………………

(ii) The ion of element G. (1 mk)

………………………………………………………………………………………………

(c) A molecule of one of the elements is shown below. (2 mks)

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(i) Identify this element from the section of the periodic table and give its actual symbol

and name. (2 mks)

………………………………………………………………………………………………

(ii) Explain why this element has a higher boiling point compared to that of oxygen.

(2 mks)

………………………………………………………………………………………………

………………………………………………………………………………………………

………………………………………………………………………………………………

(iii) Write an equation to show the reaction between the element named above with

oxygen. (1 mk)

(iv) Predict the pH of the oxide of the above element when in water. (1 mk)

………………………………………………………………………………………………

2. Use the flow chart below to answer the questions that follow.

Ammonia

Ammoniated Brine

Ammonia NH4Cl + NaHCO3

CaCl2

Substance Y

NaHCO3

Water

CO2

CaO

CaCO3

Substance X

Na2CO3

(a) Name the substances labelled: (2 mks)

X………………………………………………………………………………………

Y………………………………………………………………………………………

(b) Name 2 substances being recycled in the process represented by the flow chart. (2 mks)

………………………………………………………………………………………………

S

Slaker

T

P

R

Q

Heat

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………………………………………………………………………………………………

(c) Name the process that takes place in: (2 mks)

S.……………………………………………………………………………………………

R……………………………………………………………………………………………

(d) Give 2 uses of calcium chloride. (1 mk)

………………………………………………………………………………………………

………………………………………………………………………………………………

………………………………………………………………………………………………

(e) Write equations for the reaction that take place in: (2 mks)

Q…………………………………………………………………………………………….

………………………………………………………………………………………………

T…………………………………………………………………………………………….

………………………………………………………………………………………………

(f) Using ionic equation explain how sodium carbonate can be used to soften hard water.

(2mks)

(g) Other than softening of hard water give 2 other uses of sodium carbonate. (1 mk)

………………………………………………………………………………………………

………………………………………………………………………………………………

3. Consider this group of reaction energy profiles for some different reactions (A, B, C).

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(a) Which reaction(s) is: (2 mks)

(i) exothermic ………………………………………………………………………….

(ii) Endothermic………………………………………………………………………..

(b) Explain why the activation energy of A in diagram C is lower than the activation energy of M

in the same diagram. (1 mk)

………………………………………………………………………………………………

………………………………………………………………………………………………

(c) In an experiment to determine the heat of combustion of methanol. CH3OH, a student set up

apparatus as shown in the diagram below. Study the set up and the data and answer the


Volume of water = 100cm3

Final temperature of water = 22.00c

Initial temperature of water = 36.00c

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Final mass of lamp an methanol = 84.75g

Initial mass of lamp and methanol = 85.10g

Density of water = 1 g/cm3

(S.H.C of water = 4.2 g-1K-1)

(i) Write an equation for the combustion of methanol. (1 mk)

(ii) Calculate:

(a) Number of moles of methanol used in this experiment. (1 mk)

(b) The heat change for this experiment. (1 mk)

(c) The heat of combustion per mole of methanol. (1 mk)

(d) Explain why the molar heat of combustion for methanol obtained above is different from the

theoretical value. (1 mk)

………………………………………………………………………………………………

………………………………………………………………………………………………

(e) State two factors to consider when choosing a fuel. (1 mk)

………………………………………………………………………………………………

………………………………………………………………………………………………

………………………………………………………………………………………………

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………………………………………………………………………………………………

(f) Outline two disadvantages of using hydrogen as a source of fuel. (1 mk)

………………………………………………………………………………………………

………………………………………………………………………………………………

………………………………………………………………………………………………

4. (a) Give the IUPAC names of the following organic compounds. (2 mks)

(i) CH3 – CH2 – CH – CH3

|

CH – CH3

|

CH3

(ii) CH3 – C C – CH3

(b) Study the flow chart below and answer the questions that follow:

H2SO4(aq)

H2/ Pt

Step I Soda lime

(i) Identify (2 mks)

A……………………………………………………………………………………

B……………………………………………………………………………………

C……………………………………………………………………………………

D……………………………………………………………………………………

(ii) Explain how substance A and CH3CH3 could be distinguished by burning. (1 mk)

………………………………………………………………………………………………

………………………………………………………………………………………………

(iii) Give one reason why soda lime is preferred to pure sodium hydroxide in step I.

(1 mk)

A D

C CH3CH3

B

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………………………………………………………………………………………………

………………………………………………………………………………………………

(c) Write down the equation for the reaction between substance A and hydrogen when equal

numbers of moles are used. (1 mk)

(d) A student found a bottle containing CH3CH2COO CH3.

(i) Name the process of formation of the substance above. (1 mk)

………………………………………………………………………………………………

(ii) Identify the two substances from which the substance in (d) (i) is derived. (1 mk)

………………………………………………………………………………………………

………………………………………………………………………………………………

(e) The formulae below represents the active ingredients in a soapless detergent and in soapy

detergents respectively.

(i) Give one advantage and one disadvantage of using soapless detergent. (1 mk)

………………………………………………………………………………………………

………………………………………………………………………………………………

………………………………………………………………………………………………

(ii) Explain briefly how the soapy detergents given above may be manufactured.

(2 mks)

………………………………………………………………………………………………

………………………………………………………………………………………………

………………………………………………………………………………………………

………………………………………………………………………………………………

………………………………………………………………………………………………

5. (a) The flow chart below outlines some of the processes involved during extraction of copper

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from copper pyrites. Study it and answer the questions that follow.

Gas K Gas P

Hot air Gas K Silica (SiO2) Hot air COKE

Cu2S+ FeO CU2S Cu +

Cu2O

Slag M Cu

(i) Name gas K. (1 mk)

………………………………………………………………………………………

(ii) Write an equation for the reaction that takes place in the 1st roasting furnace.

(1 mk)

(iii) Write the formula of the cation present in the slag M. (1 mk)

(iv) Identify gas P. (1 mk)

………………………………………………………………………………………

(v) What name is given to the reaction that takes place in chamber N? Give a reason for

the answer. ( 2 mks)

………………………………………………………………………………………

………………………………………………………………………………………

………………………………………………………………………………………

………………………………………………………………………………………

(b) The copper obtained from chamber N is not pure. Draw a labeled diagram to show the set up

you would use to refine the copper by electrolysis. (3 mks)

(c) Given that the mass of copper obtained from the above extraction was 210kg, determine the

percentage purity of the ore (copper pyrites) if 810kg of it was fed to the 1st roasting furnace.

(Cu = 63.5, Fe = 56, S = 32.0) (2 mks)

Smelting

furnace 1stRoasting

Furnace

2rdRoasting

furnace Chamber

N

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(d) Give 2 effects that this process could have on the environment. (2 mks)

………………………………………………………………………………………………

………………………………………………………………………………………………

………………………………………………………………………………………………

………………………………………………………………………………………………

6. Study the scheme below and use it to answer the questions that follow:

(a) Write the formula of:

(i) Cation in solution K (1 mk)

(ii) White precipitate L (1 mk)

(iii) Colorless solution M (1 mk)

(iv) Colorless solution N (1 mk)

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(v) White precipitate P (1 mk)

(b) Write the ionic equation for the reaction for the formation of white precipitate L. (1 mk)

(c) What property of L is illustrated in the formation of colorless solution M and N. (1 mk)

………………………………………………………………………………………………

(d) Electrical conductivity decreases when temporary hard water is heated. Explain.

(2 mks)

………………………………………………………………………………………………

………………………………………………………………………………………………

………………………………………………………………………………………………

………………………………………………………………………………………………

(e) When excess iron fillings were dissolved in dilute sulphuric (IV) acid, a pale green solution

was obtained. The solution was filtered and divided into two portions.

(i) Write an equation for the reaction (1 mk)

(ii) To the first portion aqueous ammonia was added till in excess. State observation

made. (1 mk).

………………………………………………………………………………………………

………………………………………………………………………………………………

(iii) Write an ionic equation for the reaction in (ii) above. (1 mk)

7. a) State the Faraday’s law of electrolysis (1mk)

………………………………………………………………………………………………

………………………………………………………………………………………………

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b) Calculate how long it would take an aqueous gold (III) chloride cell to coat 2.5 g of gold

on a bracelet using a current of 2.5 A. The half reaction has been provided for you.

(Au = 197) (3mks)

Au3+ (aq) + 3e- Au(s)

c) Two half-cells are connected under standard conditions to make an electrochemical cell.

The two half-cells are a copper-copper (I) ion (Cu/Cu+) and an aluminum-aluminum ion

(Al/Al3+). Using your the Standard Reduction Potentials below answer.

Al3+(aq) + 3e- → Al(s) -1.66 V

Cu+(aq) + e- → Cu(s) + 0.52 V

(i) Write the cell representation for the cell obtained when the two half cells are

connected. (2mks)

(ii) Identify the reaction that takes place at the anode and at the cathode. (2mks)

………………………………………………………………………………………………

………………………………………………………………………………………………

………………………………………………………………………………………………

(iii) Calculate the emf for the above cell (1mk)

(iv) Write the overall balanced redox reaction for the electrochemical cell. (1mk)

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d) An excess of copper solid is dropped into a solution which contains AgNO3 , Fe (NO3)3 and

Zn (NO 3)2. Write the equations for any reduction half-reactions that occur over time under

standard conditions. (1mk)

KCSE MOCK 9

233/1

CHEMISTRY

Paper 1

Time: 2 Hours

01. A13+ and Na+ have the same electron arrangement.

a) Give the electron arrangement. (1 mk)

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________________________________________________________________________

b) Explain why more energy would be required to remove an electron from A13+ than Na+.

(2 mks)

________________________________________________________________________

________________________________________________________________________

02. In terms of structure and bonding. Explain why at room temperature water is a liquid while

Carbon (IV) Oxide is a gas. (2 mks)

________________________________________________________________________

________________________________________________________________________

03. Study the scheme below and answer the questions that follow:

a) State the condition and reagents required in step I and II.

Condition Reagents

I

II

(2 mk)

b) What observation is made in step (IV). (1 mk)

________________________________________________________________________

c) Give the formula and name of compound B. (1 mk)

________________________________________________________________________

d) Draw polymer A using 4 monomers. (1 mk)

________________________________________________________________________

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04. Write two equations to show that Aluminium Oxide is amphoteric. (2 mks)

___________________________________________________________________________

___________________________________________________________________________

05. The diagram below shows a set up for preparation and collection of chlorine gas.

a) What is the function of

(i) M _____________________________________________________ (1 mk)

(ii) Manganèse (IV) Oxide _________________________________________ (1 mk)

b) Give two physical properties of chlorine. (2 mk)

_____________________________________________________________________

_____________________________________________________________________

c) Chlorine gas is bubbled through aqueous Sodium Bromide.

i) State the observation made during the reaction. (1 mk)

__________________________________________________________________

__________________________________________________________________

ii) What property of Chlorine is shown is this reaction. (1 mk)

_____________________________________________________________________

06. In an experiment, Sulphur (IV) Oxide gas was bubbled into beaker of water. To the mixture

formed chlorine gas was also bubbled. The resulting mixture gave a white precipitate with

acidified Barium Chloride. Explain these observations (3 mks)

___________________________________________________________________________

___________________________________________________________________________

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___________________________________________________________________________

07. 30 cm3 of 0.2M Sulphuric (VI) acid were reacted with 30cm3 0.2M Sodium hydroride.

a) Write an equation for the reaction that took place. (1 mk)

________________________________________________________________________

b) State and explain the observations that were made when phenolphthalein indicator was added

to the mixture. (2 mks)

________________________________________________________________________

________________________________________________________________________

08. The diagram below shows a set up for preparation of oxygen gas.

a) Name solid P. (1 mk)

________________________________________________________________________

b) Write an equation for the reaction that took place. (1 mk)

_______________________________________________________________________

c) Name 2 other reagents that could be reacted in the set up above to produce oxygen.

(1 mk)

________________________________________________________________________

09. When excess Lead (II) Nitrate was reacted with Sodium Chloride a precipitate weighing 5.56g

was formed. Determine the Mass of Sodium Chloride that reacted. (3 mks)

(pb=207, cl=35.5, Na=23)

________________________________________________________________________

________________________________________________________________________

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_________________________________________________________________________

10. A sample of water is suspected to contain Sodium Sulphate. Given the following describe 2 tests

to be carried out to confirm presence of Sodium Sulphate in water.

Glass rod

Flame

Acidified Barium Nitrate

Test Description Observation Inferences

1 mk

1 mk

(1 mk)

1 mk

1 mk

1 mk

11. State and explain the observations made when Hydrogen Sulphide gas is bubbled through a

solution of Iron (III) Chloride. (2 mks)

____________________________________________________________________________

____________________________________________________________________________

12. In an experiment Hydrogen Chloride gas is bubbled through separate beakers containing water

and Methyl benzene. Explain what happens when Magnesium is added to the solutions formed.

(2 mks)

____________________________________________________________________________

____________________________________________________________________________

13. Study the formation in the table below and answer the questions that follows:-

Salt Solubility (g/100g of water)

60oC 30oC

Copper Nitrate 40 25

Magnesium Chloride 90 70

A mixture of 38g of Copper Nitrate and 66g Magnesium Chloride in 100g of water at 70oC is

cooled to 30oC.

a) Which salt will crystallise out and what mass of crystals is collected? (2 mks)

_________________________________________________________________________

_________________________________________________________________________

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b) Name the above method of separation. (1 mk)

_________________________________________________________________________

14. a) What is hard water? (1 mk)

________________________________________________________________________

b) Give an advantage and a disadvantage of using hard water.

Advantage ____________________________________________________ (1 mk)

Disadvantage ____________________________________________________ (1 mk)

15. Draw and name 2 isomers of C4H9Br. (2 mks)

16. a) What is an efflorescent salt? (1 mk)

_________________________________________________________________________

b) Give an example of an efflorescent salt. (1 mk)

_________________________________________________________________________

17. An element X has two isotopes 35X and 37X. Calculate percentage abundance of each isotope if

the relative atomic mass of X is 35.5.

(3 mks)

____________________________________________________________________________

____________________________________________________________________________

____________________________________________________________________________

18. The diagram below shows a set up of apparatus which was used to investigate the effects of an

electric current on molten Copper (II) Chloride.

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a) Name apparatus Q. ____________________________________________ (1 mk)

b) On the diagram label anode and cathode. (1 mk)

c) Write equation for the reaction at the anode. _______________________ (1 mk)

d) What observation is made at the cathode? _____________________________ (1 mk)

e) What precaution should be taken when carrying out this experiment? (1 mk)

________________________________________________________________

19. Determine the volume of 2.0 m Sodium Hydroxide which when diluted to 250 cm3 would

produce a 0.8 m Sodium Hyroxide solution. (2 mks)

____________________________________________________________________________

____________________________________________________________________________

20. In an experiment to determine the molar enthalpy of solution of concentrated Sulphuric (VI) acid,

2cm3 of the concentrated acid was added to 48cm3 of distilled water in a lagged plastic beaker. A

temperature rise of 5oC was noted.

a) Why was the beaker lagged. (1 mk)

_________________________________________________________________________

b) Calculate the molar enthalpy of solution of concentrated Sulphuric (VI) acid.

(Density of solution = 1g/cm3, C=4.2 J/g/k, density of concentrated Sulphuric acid =

1.84g/cm3, H=1, S=32, 0=16) (3 mks)

_________________________________________________________________________

_________________________________________________________________________

_________________________________________________________________________

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21. 200 cm3 1M ethanoicacid and 200 cm3 1M Hdrochloric acid were separately reacted with marble

chips. After thirty seconds it was noted that the volume of gas produced with Hydochloric acid

was higher than with ethanoic acid.

a) Identify the gas produced. (1 mk)

________________________________________________________________________

b) Why was the volume of gas produced with ethanoic acid lower? (2 mks)

_________________________________________________________________________

_________________________________________________________________________

22. a) Using dots (.) and crosses (x) to represent electrons show bonding in the following.

i) Water (H=1, 0=16) (1 mk)

ii) Calcium Oxide (Ca=20, 0=16) (1 mk)

___________________________________________________________________

iii) Give two properties of substances with giant ionic structures. (2 mks)

___________________________________________________________________

___________________________________________________________________

23. The graph below shows the relationship between pressure and temperature of a gas in a closed

system.

Volume

Pressure

a) What is the relationship between pressure and volume? (1 mk)

_________________________________________________________________________

b) Whose gas law is represented in the graph? (1 mk)

_________________________________________________________________________

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24. When 2.5 g of hydrated Sodium Carbonate (Na2CO3.XH2O) was reacted with excess

Hydrochloric acid, 300cm3 of Carbon (IV) Oxide was collected at room temperature and

pressure.

Calculate the value of x in one mole of hydrated Sodium Carbonate (H=1, C=12, 0=16,

MGV=24000cm3). (3 mk)

____________________________________________________________________________

____________________________________________________________________________

____________________________________________________________________________

____________________________________________________________________________

25. A student was supplied with a colourless liquid suspected to be water.

a) Describe two chemical tests that could have been done to confirm the liquid is water.

(2 mks)

_________________________________________________________________________

_________________________________________________________________________

b) Give one physical property of pure water. (1 mk)

_________________________________________________________________________

26. Graphite is one of the allotropes of Carbon.

a) What are allotropes? (1 mk)

_________________________________________________________________________

b) Explain why graphite is soft. (2 mks)

_________________________________________________________________________

_________________________________________________________________________

27. What name is given to elements between group (II) and group (III) in the periodic table?

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KCSE MOCK 9

233/2

CHEMISTRY

Paper 2

Time: 2 Hours

1.In an experiment of diluting concentrated sulphuric (vi) acid, 2 cm3 of acid were carefully poured

into a plastic beaker containing exactly 40cm3 of distilled water with a room temperature of 200c.

The mixture was stirred with a thermometer; the highest temperature noted was 350c. (Density of

acid = 1.84g/cm3 while that of solution is assumed to be 1g/cm3. The acid is 98% pure, S.H.C.

=4.2J/g/k H = IS = 32O = 16)

a). i). Determine the number of moles of the acid that dissolved (2 mks)

ii). Determine the enthalpy change for the reaction. (2mks)

iii). Determine the enthalpy change when one more of the acid is dissolved in water.

(2 mks)

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b) The following are standard enthalpies of formation for some compounds.

C3H8(g) ΔHƟ = -104 KJ moL-1

C3H7CL(g) ΔHƟ = -105 KJ moL-1

HCL(g) ΔHƟ = -92 KJ moL-1

Cl2(g) 𝛥H𝜽= -327Kjmol-1

Calculate the enthalpy change for the reaction below (3 mks)

Cl2(g) + C3H8(g) C3H7Cl(g) + HCL(g)

2. Use the information in the scheme below to answer the questions that follow.

Step vii

CH3COOCH2CH2CH2CH3

a) Name substance P

(1mk)

b) Give the structure and name of compound Q.

(1mk)

P

Products Butan -1-0L Hydrogen

gas

CH3CH2CH=CH2

Butan -1-01 Q

Step I

Step III

Burn

Step II

K2Cr2O7

Step IV

Conc. H2SO4

+ H2O

Step VI

Step V

H2/Nickel catalyst

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c) Write the equation for the chemical reaction in steps III

(1mk)

d) Name the reagents and conditions necessary for the reaction in

(i) Step IV

Reagents (1mk)

Conditions (1mk)

(ii) Step VII

Reagents (1mk)

Conditions (1mk)

e) What name is given to the reaction in step VII? (1mk)

f) Below are two reactions showing how a long chained alkanoic acid can be converted into

detergent B.

I. CH2 — C17H35COOH

|

CH — C17H35COOH +3H2O 3C17H35COOH + C3H8O3

|

CH2 — C17H35COOH

II. 3C17H35COOH + 3NaOH C17H35COONa + 3H2O

(detergent B)

(i) Name the type of reaction in (2mks)

I

II

(ii) Give one disadvantage of using detergent B in washing clothes. (1mk)

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3. The grid below represents part of the periodic table ( The letters do not represent the actual

symbols of the elements ).

D F

A E

B C G

(a) (i) Select an element that can form an ion with a charge of -2. (1 mark)

(ii) What type of structure will the chloride of A have. (1mark)

(iii) Explain how the reactivities of F and G. Compare (1mark)

(iv) Compare the atomic radius of C with that of B. (1 mark)

(b) 2.5g of A react completely with 1.2dm3 of gas F at S.T.P.

(i) Write a balanced equation for the reaction of A and gas F. (1 mark)

(ii) Determine the relative atomic mass of A (Molar gas volume at s.t.p = 22.4dm3) (3

marks)

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(c ) B and E burn in oxygen to form oxides.

(i) State which of the two oxides is basic and which is acidic. (2 marks)

(ii) Write down the formulae of the oxides of B and E (2 marks)

B

E

(d) An element Z consists of isotopes of masses 10 and 2 with percentage composition 18.7% and

81.3% respectively. Determine the relative atomic mass of Z

(2 mks)

4. (a) Electrolysis is used to electroplate objects among other uses. With the help of a

diagram describe how you can copper plate an iron spatula. (2mks)

(b) A concentrated solution of sodium chloride is electrolysed using carbon electrode. An

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electric current is passed through the solution for 15 minutes. The volume of the gas

produces at the cathode is 447.6cm3. Calculate the current used. (Molar gas volume at r.t.p =

24 dm3, 1F = 96500C).

(3mks)

(c) Study the standard electrode potentials for the elements given below and answer the

questions that follow. The letters are not the actual symbols of the elements.

Half reaction E0 volts

76.0Ve2V

13.0Ue2U

00.0Te2T2

23.1Se2S

36.1R2e2R

87.2Q2e2Q

)s(

2

)aq(

)s(

2

)aq(

)s(2)aq(

)s()aq(

)aq()g(2

)aq()aq(2

(i) What is the E0 value of the weakest reducing agent? (1mk)

(ii) Draw and label an electrochemical cell between elements S and V. (3mks)

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(iii) Determine the electromotive force E0 value of the electrochemical cell in (ii)

above. (1mk)

(d) In an electrolysis of a molten metal halide, a current of 1.25A was passed for 20 minutes

(i) Calculate the quantity of electricity used (1 mk)

(ii) Determine the mass of the metal deposited given that the metal is divalent [R.A.M of

metal M = 207; IF = 96,500c] (2 mks)

5. Lead (II) oxide reacts with both Nitric (V) acid and Potassium hydroxide solution

(a) What property of Lead (II) oxide is shown by these reactions? (1 mk)

(b) Write an equation for the reaction between:

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I. Lead (II) oxide and Potassium hydroxide (1 mk)

II. Lead (II) oxide and Nitric (V) acid (1 mk)

(c) The flow chart below shows a reaction scheme starting with solution A

(i) Name the type of reaction taking place in step 3 (1 mk)

(ii) Identify the cation present in solution A (1 mk)

(iii) Write the formula of the complex ion present in solution B (1 mk)

(d) (i) A solution of Hydrogen chloride gas in Carbon tetrachloride does not provide bubbles

when marble chips are placed in it, while a solution of the same gas in water provides

bubbles. Explain (2 mks)

(ii) Calculate the volume of 3M Hydrochloric acid that is needed to react completely with

0.4g of Calcium powder (Ca = 40) (3mks)

STEP 1

STEP 2

SOLUTION

A

COLOURLESS

SOLUTION

COLOURLESS

SOLUTION B

COLOURLESS

SOLUTION

WHITE

PRECIPITATE

NaOH(aq)

EXCESS

NaOH(aq)

STEP 3 H2SO4 (aq)

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6 (a) The diagram below illustrates how sulphur is extracted by the Frasch process

i) Which pipe is the hot compressed air pumped in? ( 1 mark

ii) State one physical properties that enables the sulphur to be extracted by frasch process.

(1mark

b) The diagram below shows an incomplete set-up used to prepare and collect sulphur(IV)oxide gas.

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i) Complete the diagram to show how a dry sample of sulphur(IV)oxide gas can be collected.

(2marks

ii) Write an equation for the reaction in the flask.

(1mark

iii) State the observation made when sulphur (IV) oxide gas is bubbled through iron (III) sulphate

solution in a test-tube.

(1mark

c) The equation below shows the oxidation of sulphur (IV) oxide to sulphur(VI)oxide in contact

process.

2SO2(g) + O2 (g) 2 SO3(g)

i) Name one catalyst for this reaction. ( 1 mark

ii) Describe how sulphur (VI)oxide is converted to sulphuric(VI)acid in the contact process.

(2marks)

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iii) Give one reason why it is necessary to use a pressure of 2 to 3 atmospheres and not more in

the contact process.

(1mark)

d) Ammonium sulphate is a fertilizer produced by passing ammonia gas into concentrated

sulphuric(VI)acid as shown in the equation below;

3( ) 2 4( ) 4 4( )22 l sNH H SO NH SO g

Calculate the mass in kg of sulphuric(VI)acid required to produce 25kg of the fertilizer.

(S=32.0, O=16.0; N=14.0; H=1.0)

(3marks

7. a) State Graham's law of diffusion. (1 mark)

b) An experiment was carried out to compare the rates of diffusion of chlorine gas and

hydrogen sulphide gas. (H=1, S=32, Cl=35.5)

Combustion tube

Chlor

ine hydrogen sulphide

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Pressure (Pascals) 101325 103221

Volume (cm³) 80 100 120

i) What observation was made in the combustion tube? (1 mark)

ii) Indicate where the observation in (i) above would occur. (1 mark)

iii) It takes 15 seconds for 45cm³ of chlorine to diffuse through the combustion tube. How long will it take 135cm³ of hydrogen sulphide to diffuse under similar conditions? (3 marks)

c) i) Complete the table below involving variation of volume with pressure at constant

temperature. (3 marks)

ii) State the law being investigated in (i) above. (1 mark)

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KCSE MOCK 10

CHEMISTRY FORM FOUR

Paper 1

FORM IV CHEMISTRY PP1. 233/1

1. The diagram below shows the set-up of apparatus used to separate methanol

(boiling point 65oC) and water (boiling point 100oC)

Identify:- a) apparatus X --------------------------------------------------------------------

(1mk)

b) apparatus Y -------------------------------------------------------------------------------

(1mk)

c) Liquid Z ---------------------------------------------------------------------------------------

(1mk)

2. The flow chart below shows some processes involved in the industrial extraction of

zinc metal.

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a) Name one ore from which zinc is extracted (1mk)

--------------------------------------------------------------------------------------------------------

-----b) Write the equation for the reaction taking place in unit II (1mk)

--------------------------------------------------------------------------------------------------------

-----c) Name two uses of zinc metal.(1mk)

i)

ii)

3. The diagrams below represent two iron nails with some parts wrapped tightly with

zinc and copper strips, respectively.

What observations would be made at the exposed points A and B if the wrapped nails

are left in the open for several months? Explain. (3mks)

Observation at A –

Explanation:-

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Observation at B:-

4. The diagram below shows chromatogram for three dyes.

a)Which pure dye is not present in the mixture E? (1mk)

b) Which of the three pure dyes is the least sticky. Give a reason. (1mk)

c) Show on the diagram, the solvent front. (1mk)

5. In the equation below, identify the reactant that acts as an acid. Explain (2mks)

6. A compound C4H10O, is oxidized by excess acidified potassium permanganate to

form another compound, C4H8O2. The same compound C4H10O reacts with potassium

to produce hydrogen gas.

a) Draw the structural formula and name compound C4H10O. (1mk)

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b) Write an equation for the reaction between potassium and compound C4H10O.

(1mk)

--------------------------------------------------------------------------------------------------------

-----

7. Element R – 238 decays in series forming different nuclides as shown below:-

a) Identify the type of decay.(2mks)

X ------------------------------------------------------------Y --------------------------------------

----

b) Give one use of radioactive isotopes. (1mk)

--------------------------------------------------------------------------------------------------------

-----

8. Explain how the rates of diffusion for equal quantities of nitrogen and oxygen

gases compare under the same conditions. (N=14, O=16) (2mks)

9. When 34.8g of hydrated sodium carbonate (Na2CO3 H2O) were heated to a

constant mass, 15.9g of anhydrous sodium carbonate were obtained. Calculate the

value of X in the hydrated carbonate. (Na=23, O=16, C=12, H=1) (3mks)

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10. During purification of copper by electrolysis 1.48g of copper were deposited when

a current was passed through copper (II) sulphate solution for 2 ½ hours. Calculate the

amount of current that was passed. (Cu = 63.5, F = 96500C) (3mks)

11. Sample solutions of salts were labelled as I, II, III and IV. The actual solutions, not

in that order, are lead nitrate, zinc sulphate, potassium chloride and calcium chloride.

a) When aqueous sodium carbonate was added to each sample separately, a white

precipitate was formed in I, III and IV only. Identify solution II. (1mk)

--------------------------------------------------------------------------------------------------------

-----b) When excess aqueous sodium hydroxide was added to each sample separately,

a white precipitate was formed in III only. Identify solution III. (1mk)

--------------------------------------------------------------------------------------------------------

-----c) When dilute sulphuric (VI) acid was added separately to each sample, a white

precipitate was formed in solutions I and III only. Identify solution I (1mk)

--------------------------------------------------------------------------------------------------------

-----

12. Study the table below and answer the questions that follow:-

Alkane Formula Heat of combustion ( Hc) KjMol-

Methane CH4 -890

Ethane C2H6 -1560

Propane C3H8 -2220

Butane C4H10

a) Predict the heat of combustion of butane and write it on the space provided in the

table above. (1mk)

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157

b) What does the sign of Hc value indicate about combustion of alkanes? (1mk)

13. a) What are isotopes. (1mk)

b) Element X(not actual symbol of the element) has two isotopes with mass no.s 6 &

7. If the relative atomic mass of x is 6.94, determine the % abundance of each isotope.

(2mks)

14. Complete the table below:- (1mk)

Isotope Number of

Protons Neutrons Electrons

15. On the axis below, sketch a graph to show how pressure varies with volume for

fixed mass of an ideal gas at constant temperature. (2mks)

16. Study the set-up below and use it to answer the questions that follow:-

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a) Identify R --------------------------------------------------------------------------------(1mk)

b) State the function of concentrated Sodium hydroxide solution. (1mk)

c) State the property of carbon (II)oxide gas demonstrated in the above set-up. (1mk)

17. a) Both chlorine and iodine are halogens.

a) What are halogens? (1mk)

b) In terms of structure and bonding, explain why boiling point of chlorine is lower

than that of Iodine. (2mks)

18. Describe how the following reagents can be used to prepare lead sulphate. (2mks)

- Solid potassium sulphate

- Solid lead carbonate

- Dilute nitric acid

- Distilled water

19. Identify the particles which enable the following substances to conduct electricity.

i) Magnesium metal (1mk)

ii) Molten lead (II) bromide (1mk)

20. Below is an arrangement which was used to prepare gas X.

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i) Which one property of gas X can you tell from the method of preparation? (1mk) ---

-------------------------------------------------------------------------------------------------ii)

Identify gas X -----------------------------------------------------------------------------(1mk)

iii) Why is lead (II) nitrate more suitable than other nitrates for the preparation of gas

X. (1mk)

21. The diagrams below shows the bonding between aluminium chloride and

ammonia.

a) Name the types of bonds that exist in the molecule. (1mk)

b) How many electrons are used for bonding in the molecule?(1mk)

22. 100cm3 of methane gas diffused through a porous partition in 40 seconds. How

long would it take 90cm3 of ozone gas to diffuse through the same partition? ( C=12,

H=1, O=16) (3mks)

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23. The equilibrium between nitrogen (IV) oxide and dinitrogen tetraoxide is

represented by the equation

Given that the decomposition of dinitrogen tetraoxide is endothermic, what

observation would be made if the equilibrium mixture was heated. Explain. (2mks)

24. A student set-up the experiment below to collect gas K. the glass wool was heated

before heating the zinc powder.

Why was it necessary to heat the moist glass wool before heating zinc powder? (1mk)

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b) What would happen if zinc powder was heated before heating the glass wool?

(1mk)

c) What property of gas K makes it possible for it to be collected in the diagram?

(1mk)

25.a) Name a substance that reacts with water to give oxygen gas. (1mk)

--------------------------------------------------------------------------------------------------------

-----

b) Write an equation for the reaction. (1mk)

--------------------------------------------------------------------------------------------------------

-----

Q26. Propane and chlorine react as shown below:

a) Name the type of reaction that takes place. (1mk)

--------------------------------------------------------------------------------------------------------

-----

b) State the condition under which this reaction takes place.(1mk)

--------------------------------------------------------------------------------------------------------

-----

c) Propane can be changed into methane and ethane as shown in the equation below:-

CH3 CH2 CH3(g) High temperature CH4(g) + C2 H4(g)

Name the process undergone by propane. (1mk)

27. The pH of a sample of soil was found to be 5.0. An agricultural officer

recommended the addition of calcium oxide in the soil. State two functions of the

calcium oxide in the soil. (2mks)

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28. The table below gives the atomic numbers of elements W, X, Y and Z. the letters

do not represent the actual symbols of the elements.

Element W X Y Z

Atomic Number

a) Which one of the elements is least reactive? Explain? (1mk)

b)(i) Which two elements would react most vigorously with each other? (1mk)

--------------------------------------------------------------------------------------------------------

-----(ii) Give the formula of the compound formed when the elements in (b(i) above

react.--------------------------------------------------------------------------------------------

(1mk)

29. Explain the changes that occur when sulphur is heated until it reaches its boiling

point. (3mks)

30. A polymer has the following structure.

CH2 CH CH2 CH CH2 CH

CN CN CN

A sample of this polymer is found to have a molecular mass of 5194. Determine the

number of monomers in the polymer . (H=1.0, C = 12.0, N = 14.0) (3mks)

31. What is the oxidation number of:-

a) sulphur in S2O32- (1mk)

b) Explain why hydrogen forms compounds in which its oxidation state is either +1 or

-1. (Atomic number of hydrogen is 1) (2mks)

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KCSE MOCK 10

CHEMISTRY MOCK PP2

Q1. (i) The grid below shows part of the periodic table. Study it and answer the

questions that follow. The letters do not represent the actual symbols of the

elements.

J J

A

B C D E

F G

H

a) Which element forms ions with charge of -2? Explain. (1mk)

b) What is the nature of the oxide formed by C? (1mk)

c) How does the reactivity of H compare with that of E? Explain. (2mks)

d) Write a balanced equation for the reaction between B and Chlorine. (1mk)

e) Explain how atomic radii of the following compare.

(i) F and G (1 ½ mks)

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(ii) B and G (1 ½ mks)

f) If the oxide of B and D are separately dissolved in water, what effects with

their aqueous solutions have on litmus? (1mk)

g) Element J can be placed on the two positions shown in the grid. Explain this:-

(2mks)

Q2.a)(i) Give the IUPAC name of:-

CH3CH2C CH

ii) Write a chemical equation of the reaction between the substance in a(i) above and

hydrogen chloride. Give the structure and name of the product.

Equation:-

Structure of the product –

Name of the product –

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b) Study the reaction scheme below and answer the questions that follow:-

i) Name compound:- (1mk)

S –

T –

ii) State the conditions/reagents necessary for the process to take place in:- (4mks)

Step I –

Step II –

Step VI –

Step V –

iii) Write an equation for the formation of compound S. (1mk)

iv) Give one advantage of use of compound T over natural polymer. (1mk)

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v(i) What is a thermosetting plastic? (1mk)

ii) Natural rubber is made from the monomer unit isoprene.

Draw the polymer unit of natural rubber showing 2 monomer units. (1mk)

iii) Why is it necessary to vulcanise rubber before use? (1mk)

Q3. In an experiment to determine the heat of precipitation of silver chloride, 25cm3

of 2M silver nitrate was added to 25cm3 of 2M sodium chloride in a plastic beaker.

The mixture was stirred gently and its steady temperature noted. Use the data below

to answer the questions that follow:-

Average original temperature of solutions = 25.0o

Steady temperature of the mixture = 34.0oC

Density of the mixture = 1.0g/cm3

Specific heat capacity for the mixture = 4.2kJ/kg/oC

a)(i) Why was a plastic beaker preferred in this experiment. (1mk)

(ii) What could have been done to the plastic beaker to increase the accuracy of the

results in this experiment? (1mk)

b)(i) Calculate the heat change that occurs in this experiment. (1mk)

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(ii) Write the equation for the reaction that occurs. (1mk)

(iii) Calculate the number of moles of silver chloride precipitated. (1mk)

iv) Calculate the molar enthalpy of precipitation of silver chloride. (1mk)

v) Write a thermal ionic equation for the reaction. (1mk)

c) Study the thermal chemical equation for the formation of water and the bond

energies below and answer the questions that follow:-

Bond Bond Energies (kJ Mol-1)

O = O 496

H – H 435

H - O

H2(g) + ½ O2 H2O(l) H = -287kJMol-1

i)Draw an energy level diagram for the reaction. (1mk)

ii) Calculate the bond energy for the bond between H and O in a water molecule and

use the results to complete the table above. (2mks)

d)(i) Calculate the heating value of hexane C6H14 given that its heat of combustion is

4128kJMol-1. (C=12.0, H=1.0) (2mks)

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(ii) Give a factor which one needs to consider when choosing a fuel apart from its

heating value. (1mk)

4. Below is a Down’s cell used in the extraction of sodium metal.

a) What is the purpose of calcium chloride. (1mk)

b) Write the equation that occurs at the:- (2mks)

(i) Anode –

(ii) Cathode –

c) What is the function of steel diaphragm? ( ½ mk)

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d) Name substance P …………………………………………………………………….( ½ mk)

e) Iron is extracted by heating its ore with coke. Explain why it is not possible to

use this method for extraction of sodium. (2mks)

f) State two observations made when a grain of sodium metal is placed in water.

(1mk)

g) Explain why it is advisable to use a pair of tongs when holding sodium. (1mk)

h) How is sodium stored in the laboratory. Explain. (1 ½ mks)

i) Give one use of sodium. ( ½ mk)

5. Use the standard electrode potentials given below to answer the questions that

follow:-

i)Identify the strongest reducing agent. Explain. (2mks)

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ii) In the space provided. Draw a well labeled diagram of a conventional

electrochemical cell that would be obtained when the two half cells B(s)/B2+(aq) and

C(s)/C2+(aq) are combined. (2mks)

iii) Write the cell representation of the cell and then calculate the over e.m.f of the

cell. (2mks)

iv) A molten liquid containing the ions of metals B and C was electrolyzed using inert

electrodes. Write an equation for the reaction that occurs at the cathode. (1mk)

b)(i) 10.26g of aluminium sulphate were dissolved in water to make 200cm3 of

solution. Calculate the molar concentration of the sulphate ions in the solution. (Al =

27, S = 32, O = 16) (3mks)

(ii)When barium chloride was added to the solution formed above to react fully a

white precipitate was formed. Calculate the mass of the white precipitate formed.

(Ba = 137, S = 32, O = 16). (2mks)

6. The diagram below represents the extraction of sulphur by the frasch process.

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i)Identify and state the use of the substance that pass through A and C. (2mks)

A –

C –

ii) Rhombic and monoclinic are allotropes of sulphur. They are interconvertible as

shown below:-

i)What does the temp. 96oC represent.

-------------------------------------------------------------------------------------------------------------

ii) State the difference in crystalline appearance between rhombic and monoclinic

crystals. (1mk)

b) The following scheme represents the steps followed in the contact process. Study

it and answer the questions that follow:-

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i)Name the possible identities of solid A. (1mk)

ii) Name one impurity removed by the purifier. (1mk)

iii) Why is it necessary to remove impurities. (1mk)

iv) Name the catalyst which is preferred in this process and why? (2mks)

v) Explain an environmental effect of sulphure (IV) oxide in the atmosphere. (2mks)

7. a) What is meant by saturated solution. (1mk)

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b) The solubilites in grams of sodium nitrate in 100g of water are given for various

temperatures in oC.

Temperatures oC

0 10 20 30 40 50 60 80 90 100

Solubilityg/100g

of water

73 80 88 96 104 114 124 148 162 180

i)Draw on graph paper the solubility curve for sodium nitrate. (3mks)

ii) From the graph evaluate the solubility at 70oC (1mk)

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174

iii) 100g of a solution of sodium nitrate is in the saturated condition at 10oC. How

many grams of the salt would have to be added to make the solution just saturated

at 80oC. (3mks)

FORM 3 2013 PAPER 1 EAST ZONE CHEMISTRY

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