MOCK EXAMINATION - JANUARY, 2013

ELECTIVE CHEMISTRY TIME: 3 HOURS

PART A (5O MARKS)

OBJECTIVE TEST

Select the most appropriate option from those lettered A TO D

1. What is the hydrocarbon in the equation?2CxHy + 7 O2 4CO2 + 6H2O

A. ButaneB. EthyneC. EthaneD. Ethene

2. The structure of 2- hydroxypropanoic acid is ……………………………..

A. B.

C. D.

3.Which of the following compounds have stereo isomers?

I. CH3CH=CHCl

II. CH3CH=CHCH3

III. (CH3)2C=CHCH3

IV. CH3CH2CH=CHCH3

A. I and II only B. III and IV only

C. I, II, and III only C. I, II, and IV only

4.The IUPAC name for CH3CH(CH3)CHClCH(CH3)CH2CH3 is …………………………..

A. 2, 4-dimethyl-3-chlorohexane

B. 3, 5-dimethyl-4-chlorohexane

C. 4-chloro- 3, 5- dimethylhexane

D. 3-chloro-2, 4-dimethylhexane

5. Designs on the glass vessels can best be made with ……………………………

A. Glass-tripped pencilsB. Graphite-tipped pencilsC. Lead-tipped pencilsD. Diamond-tipped pencils

6. The number of neutrons in 146 C is ……………………………………..

A. 20B. 14C. 8D. 6

7. The electronic configuration of chromium is [Ar] 3d5 4s1 and not [Ar] 3d4 4s2 because of the ……..

A. Extra stability of the half-filled d-orbitals.B. High energy of the s-orbital.C. Low energy of the d-orbital.D. Unstable nature of the s-orbital

8. The shape of a p-electron orbital is like that of …………………………………

A. Two pyramids touching each other at their bases.B. Two spheres touches each other.C. Two circles touching each other.D. A tetrahedron.

9. Three isotopes of the same element are represented as 12xA, 13

yB , and dzC.

Given that y =122

and d= x+Z+2, find the number of neutrons in C.

A. 2B. 4C. 6D. 8

10. Which of the following is not accounted for by Dalton’s Atomic Theory?

A. The constitution of elements.B. Indestructibility of atoms.C. Isotopy and radioactivityD. The chemical combinations of atoms

11. Which of the following substances has metallic bonding?

A. DiamondB. AluminaC. VanadiumD. Silicon

12. In the periodic table all the elements within the same group have the same …………….

A. Number of isotopes.B. Atomic number.C. Number of neutrons the nuclei of their atom.D. Number of electrons available for bonding.

13. Pi – bonds are formed by the ………………………………………..

A. Head – overlap of two p – orbitals.B. Lateral overlap of two parallel p – orbitals.C. Overlapping of two s- orbitals.D. Head – on overlap of a s – orbital and p – orbital

14. Graphite is used as a lubricant because ……………………………………

A. Weak Van de Waal’s forces exist with each of its layer structures.B. Weak Van der Waal’s forces exist between its layer structures.C. Strong covalent bonds exist between its layers.D. Strong covalent bonds exist within each of its layer structures.

15. Which of the following processes is used in the food preservation industry?

A. Nuclear fission B. Nuclear fusionC. Irradiation with gamma raysD. Carbon – 14 dating

16. From the equation : -

147 N + 4

2 He 178 O + 1

1 Z, Z is

A. An electronB. A helium nucleusC. A protonD. A gamma ray

17. The reaction 22688Ra 222

86 Rn + 42 He, can be described as:-

A. Alpha – decayB. Beta – decayC. Proton – decayD. Gamma –decay

18. A nuclear reaction which results in the conversion of one element to another is known as……..

A. RadioactivityB. TransmutationC. Nuclear fusionD. Nuclear fission

19. Which of the following reaction will occur in a nuclear reactor ?

A. 23592U + 1

0 n 9038Sr + 143

54Xe + 310 n

B. 2311 Na + 1

0 n 2412Mg + 0

-1eC. 14

7 N + 10n 14

6C + 11 H

D. 11H +1

1 H 21H + 0

+1e

20. The half –life of a radioactive material is 1 week or 7days.How much of the material is

expected to remain if 80.0g of it is left for 42 days?

A. 1.25gB. 2.50gC. 5.00gD. 10.00g

21. The electron configuration which is wrongly given as 1s2 2s2 2p3x 2p1

y 2p0z violates

the ………

A. Hund’s rule only.

B. Pauli’s exclusion principle only .C. Aufbau and pauli’s exclusion principles.D. Pauli’s exclusion principle and Hund’s rule.

22. A substance X dissolves readily in water. X is likely to be ?

A. An ionic compoundB. A covalent compound C. A non-metalD. A metal

23. Which of the following compounds is covalent?

A. Sodium hydroxide B. Silver nitrateC. Ammonium chlorideD. Sugar

24. A compound formed by the combination of elements in the same period with large

differences in their electronegativity values is likely to be ?

A. Giant moleculeB. IonicC. Simple molecular D. Polar covalent

25. From the equation

CH4(g) C(S) + 4H(g) , H = +1662kJmol-1

The C-H bond energy is ?

A. +1662.0 kJmol-1

B. +554.0 kJmol-1

C. +415.5 kJmol-1

D. +332.4 kJmol-1

26. The enthalpy of combustion HƟcomb. of C(s) in the reaction C(S) + o2(g)

CO2(g) could

also be referred to as enthalpy of ?

A. Formation of C(s)

B. Formation of CO2(g)

C. Combustion of O2(g)

D. Combustion of CO2(g)

27. Given that;

C2H4 + 302(g) 2CO2(g) + 2H2O(l) , HƟcomb = -1450KJmol-1

C(s) + O2(g) CO2(g) , HƟcomb=-400KJmol-1

H2(g) + 12

O2(g) H2O(l) , HƟcomb=-300KJmol-1

Calculate the heat of formation of ethene from the equation

2C(s) + 2H2(g) C2H4(g)

A. +50KJmol-1

B. +450KJmol-1

C. +750KJmol-1

D. -2150KJmol-1

28. When 100.0cm3 of 0.1M NaOH is mixed with 100cm3 of 0.15M NaOH, the

concentration of the resulting solution will be?

A. 0.013 moldm-3

B. 0.025moldm-3

C. 0.125moldm-3

D. 0.250moldm-3

29. Student X titrated 25.0 of 0.1M K2CO3 with 0.1M HCl, using methyl orange as

as indicator. Student Y carried out the same exercise but used Phenolphthalein as

indicator . Which of the following statements about the titration is true?

A. The titre value for the titration by X is half that of Y.B. The titre value for the titration by X is twice that of Y.C. The titre values obtained from the two titrations are equal.D. Carbon (IV) oxide gas was released in the reactions in both titrations

30. 20.0cm3 of a saturated aqueous solution of sodium hydrogen trioxocarbonate(IV) at

25°C required 10.0cm3 of 2.0M hydrochloric acid for complete reaction.What is the

solubilty of sodium hydrogen trioxocarbonate (IV) in moldm-3 at 25°C.

A. 1.0B. 1.5C. 2.0D. 2.5

31. A known volume of an aqueous mixture of Na2CO3 and NaOH was titrated with a

standardHCl(aq) using phenolphthalein as indicator.Which of the reactions below

is/are completed at the end- point?

I. Na2CO3 + HCl NaHCO3 + NaClII. Na2CO3 +2HCl 2NaCl + H2O +CO2

III. NaOH + HCl NaCl + H2OA. I only B. II onlyC. I and II onlyD. I and III only

32. What is the solubility of a salt MX in water at 25°C if a saturated solution of MX

contains 0.28g of the salt in 100g of pure water contains 25°C?

[molar mass of MX =56gmol-1 :ƿH2O = 1gcm-3]

A. 5.60 moldm-3

B. 2.80moldm-3

C. 0.10moldm-3

D. 0.05moldm-3

33. If 40cm3 of a saturated solution of Ca(OH)2 was neutralized by 20cm3 of 0.10moldm-3

HCl, what is the concentration of Ca(OH)2 ?

Ca(OH)2 + 2HCl CaCl2 + H2O ; [relative molecular mass of Ca(OH)2 =74]

A. 0.025 gdm-3

B. 1.850gdm-3

C. 7.400gdm-3

D. 14.800gdm-3

34. When 32.5g of zinc metal reacts with excess dilute H2SO4 at standard temperature and

Pressure (stp), Calculate the volume of H2 gas liberated. (Zn =65; Vm = 22.4 dm3)

A. 44.8 dm3

B. 22.4dm3

C. 11.2dm3

D. 2.24dm3

35 .How many NO3- ions are contained in the 0.10moldm-3 Ca(N03)2 solution?

[NA =6.02 × 1023 mol-1]

A. 12.04 × 1023

B. 12.04 × 1022

C. 1.204 × 1023

D. 1.204 × 1022

36. When the volume of a fixed mass of gas decreases gradually at a certain temperature,

the particles of the gas.

A. Cease to moveB. Move around at a lower speedC. Move around at the higher speedD. Collide more frequently with each other

37. Which of the following represents the mathematical expression of Charles’ law?

A.VT

= k

B.PVT

=K

C. PV=nRTD. P1V1 = P2V2

38. The conjugate base of H2PO4-1 is …………………………….

A. H3PO4

B. HPO42-

C. H4PO4+

D. PO43-

39. Given the reaction: 3E + 4F 4G + 7H and the standard enthalpies of

formation Hf, of E = +15.7KJmol-1 ; F = -86.4 KJmol-1, G = -52.7KJmol-1,

H =- 71 KJmol-1

What is the standard enthalpy of the given reaction in KJmol-1?

A. -53.6B. -413.5C. -515.6D. -853.6

40.What is the pH of 0.001M NaOH solution?

A. 1B. 3C. 11D. 14

41. The PKa for propanoic acid is 4.9. Calculate the pH of a 0.01 solution of the acid.

A. 2.5B. 3.0C. 3.5D. 4.0

42. A suitable indicator for weak acid- strong base titration is…………………………

A. PhenolphthaleinB. Methyl redC. LitmusD. Methyl orange

43. NaCl(aq) conducts electricity to a greater extent than CH3COOH because………

A. CH3COOH contains less molecules than NaClB. NaCl contains more molecules than CH3COOHC. NaCl contains more ions than CH3COOHD. CH3COOH contains more ions than NaCl

44. The rate determining step for the reaction

2A + 3B 2C, is A + 2B D. what is order of the reaction?

A. 0B. 1C. 2D. 3

45. Consider the reaction ; 3A + 2B +C D. The rate of reaction is given by

R =K[A]2[B]2[c]. By how many time will the rate increase, if the concentration

of the reactants are doubled?

A. 4B. 8C. 16D. 32

46. The rate of chemical reactions generally increases with increasing temperature

because ………………………….

A. The number of effective collisions is higher at a higher temperatureB. The activation energy of the reaction decreases at a higher

temperatureC. The reaction mechanism at a higher temperature differs from that of a

Lower temperatureD. Masses of the reacting particles decrease at higher temperature

47. For the equilibrium reaction H2 (g) + I2 (g) 2HI(g)decreasing the volume of

the reaction vessel would ………………………….

A. Increase the rate of the reactionB. Have no effect on the equilibrium positionC. Shift equilibrium position to the rightD. Shift equilibrium position to the left

48. When 2 Faradays of electricity is passed through a solution, which of the following

quantities of ions will be discharged?

A. 1 mol of Na+

B. 1 mol of Zn2+

C. 2 mol of Ca2+

D. 3 mol of Al3+

49. Consider the equation below :

Cr2O72- + 14H+ + 6e- 2Cr3+ + 7H2O.

Cr2O72-ions are said to be reduced to chromium ions because the oxidation

Number of chromium decreases from …………..

A. 7 to 3 B. 7 to 2C. 6 to 3D. 6 to 2

50. Consider the reaction represented by the following:

Mg + Fe2+ Mg2+ + Fe

Which of the following statements about the reaction is correct ?

A. Fe2+ loses electronsB. Fe2+ is the oxidizing agentC. Mg is the oxidizing agentD. Mg is reduced

PART B

ESSAY TEST (100 marks)

Answer four (4) questions in all

All question carry equal marks.

1(a) Explain the following terms as applied in chemical kinetics:-

i. Rate of reaction

ii. Overall order of reaction(5marks)

(b) During the study of the kinetics of the reaction A + B → C + D, the following data was obtained:

ExperimentConcentration of A/moldm-3

Concentration of B/moldm-3

Rate of reaction/moldm-3s-1

1 3.0 3.0 3.7 x 10-7

2 4.6 3.0 5.7 10-7

3 4.6 7.4 14.0 x10-7

i. Determine the order of the reaction with respect to A and B.

ii. Write the rate law equation for the reaction.

iii. Calculate the specific rate constant and give it units.(9marks)

(c)i. Define activation energy.

ii. Draw and label an energy profile for an endothermic reaction. Indicate on the same diagram the effect a catalyst would have on the path of the reaction.

(6 marks)

d. A 250cm3 solution of K2Cr207 with concentration 0.025moldm-3 is to be prepared from a stock solution with concentration 0.04moldm-3. Calculate the volume of the water that will have to be added to the stock solution.

(5marks)

2(a ) i. Explain briefly the term chemical equilibrium.

ii. For a given chemical equilibrium system, what is the significance of the equilibrium constant, Kc? (4marks)

(b). Consider the reaction represented by the following equation:-V2O5

2SO2(g) + O2(g) 2SO3(g), ∆H = -ve

i. Write an expression for the equilibrium constant, Kc .

ii. Sketch the energy profile diagram for the forward reaction and show the catalysed path.

iii. State with reason, the effect of each of the following factors on the system:-

(α) increase in temperature;

(ᵦ) increase in pressure;

(ɤ) removal of some of the SO3

(ᶓ) presence of the catalyst V2O5

(14marks)

(c) When a quantity of sulphur was burnt in excess oxygen, 75.0cm3 sulphur (IV) oxide was produced at s.t.p.

i. Write the equation for the reaction

ii. Calculate the volume of oxygen used during the reaction

iii. Which of the gas laws is applied in (ii) above?

iv. State the law you have mentioned in (iii)

(Vm = 22.4dm3 mol-1 at s. t. p) (7marks)

3.a.i. Draw and label a cell diagram for the cell whose overall reaction is ;

Fe(s) + 2H+(aq) Fe2+

(aq) + H(g)

ii. Show the direction of the flow of electrons.

iii. What is the function of a salt bridge in a cell?(6marks)

b. Consider the following redox reaction:

MnO4- + Fe2+ + H+ Mn2+ + Fe3+ H2O

i. Separate the reaction into balanced half cell reactions.

CH3CHCH=CH C OOH OH

ii. Write the overall balanced reaction.(5marks)

(c )i. State three factors that influence the selective discharge of ions during electrolysis.

ii. A steady current of 2A is passed through a solution of magnesium chloride for 3 hours. Determine the mass of magnesium discharged. [Mg = 24.0; F = 96500C]

iii. State two practical applications of electrolysis.(9marks)

d.i. Define each of the following terms:-

(α) Bronsted-Lowry acid

(ᵦ) Lewis acid

ii. Classify the following as Bronsted-Lowry acid, Bronsted-Lowry base or Lewis acid

Cu2+; NH4+; HCO3

- (5marks)

4.a. Consider the following structure

i. State what will be observed when the compound is treated with

(α) bromine water

(ᵦ) hot solution of I2 in NaOH(aq)

(ɤ) Cold NaHCO3(aq)

ii. Name the functional group that is responsible for each of the observations in (i) above. (7mnarks)

(b) A saturated organic compound with two (2) carbon atoms reacted with NaHCO3 solution to give a colourless, odourless gas which turned lime water milky.

i. Name the functional group present in the compound.

ii. Draw the structure of the compound showing all the bonds.

iii. Write an equation to represent the reaction between the compound and ethanol in the presence of mineral acid.

iv. Name the organic product formed in (iii) above.(6marks)

(c )i. Draw a complete structural formula for the following compound CH3CCCH2CN

ii. Indicate the type of hybridization in each atom in the compound(4marks)

d. A hydrocarbon X with molecular mass 78, on combustion gave 3.384g of carbon (IV) oxide and 0.693g of water. Determine the molecular formula of X. [H = 1.0; C = 12.0; O = 16.0]

(8 marks)

5(a ) Define the following terms

i. saturated solution

ii. Solubility of solute (4marks)

(b) The solubility of a salt Q in moldm-3 at various temperatures is given in the table below:

Temperature/ 0C 0 10 20 30 40 50 60

Solubility of Q/moldm-3 0.68 0.74 0.84 0.96 1.12 1.32 1.60

i. Plot the solubility curve for Q, with temperature on the x-axis and solubility on the y-axis.

ii. From the graph determine the solubility of Q at 250C.

iii. If 50cm3 of a saturated solution of Q is cooled from 600C to 250C, calculate the mass of the salt Q that would be obtained.

iv. State one use of solubility curves. [Molar mass of Q = 250gmol-1] (11marks)

(c ) During titration of monocarboxylic acid with NaOH, 1.39g of the acid required 20.00cm 3 of 0.25moldm-3 of the alkali for complete neutralization. When 0.417g of the acid was catalytically hydrogenated, 100.79cm3 of hydrogen gas measured at s. t. p. was absorbed.

i. Write a balance equation for the reaction.

ii. Calculate

(α) the number of moles of the acid used

(ᵦ) the molecular mass of the acid

(ɤ) the number of moles of hydrogen that reacted with the acid.

[Molar volume of gas at s. t. p. = 22.4dm3](10marks)

6 (a) i. Define the term

(α ) radioactivity

(ᵦ) half-life

ii. State the type of decay that occurs in the following nuclear reactions:-

(α) 4021

Sc 4020

Ca + 0+1

e

(ᵦ) 22688

Ra 22286

Rn + 42

He

(6marks)

(b) Balance the following nuclear equations and identify the nuclides, X, Y, Z and A.

i. 3114

X ¿Y + 0

−1e

ii.¿ Z + 10

n 2411

A + 42

He

(c) i. Alpha particle emission by 23592

U produces an element A. Beta particle emission by the

element A produces another element B. Element B undergoes alpha particle emission to produce a third element C. Write balanced nuclear equations to represent the above statements.

(6marks)

d. The following label specifications were found on the stock bottle of concentrated H2SO4:

(Density = 1.84gcm-1,

Purity = 98%,

Mr (H2SO4) =98

Using the above information, determine the volume of distilled water that will be required to prepare 1000cm3 of 0.92moldm-3 solution of H2SO4.

(7marks)

Good Luck!!!