(1) (2) - Tasker Milwardscience.taskermilward.org.uk/mod1/KS4Chemistry/AQA... ·...

Q1. The chart shows the processes involved in the manufacture of nitric acid from ammonia.

(a) Complete the word equation for the reaction that takes place in the first reaction vessel.

ammonia + ...................................... nitrogen monoxide + water (1)

(b) What is the use of the platinum gauze in the reaction vessel?

..................................................................................................................................... (1)

(c) To convert nitrogen monoxide into nitric acid, two further reactants are needed. What are they?

................................................................ and ............................................................ (1)

(d) Complete the word equation below, to show how to make the fertiliser, ammonium nitrate.

................................ + ......................... ammonium nitrate + water (2)

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(e) Calculate the percentage of nitrogen in the fertiliser, ammonium nitrate NH4NO

3.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

(Total 7 marks)

##

Here is a symbol equation, with state symbols, for a chemical reaction between solutions of lead nitrate and potassium chloride.

Pb (NO3)

2 (aq)

+ 2 KCl (aq)

2KNO3 (aq)

+ PbCl2 (s)

The equation tells you the formulae of the two products of the reaction.

1 .................................................................................................................................

2 ................................................................................................................................. (2)

(b) What else does the equation tell you about these products?

....................................................................................................................................

....................................................................................................................................

.................................................................................................................................... (2)

(Total 4 marks)

Q3. Here is a word equation for a chemical reaction.

copper oxide + sulphuric acid copper sulphate + water

Write down everything that the word equation tells you about the reaction.

...............................................................................................................................................

...............................................................................................................................................

............................................................................................................................................... (Total 4 marks)

(a) What are the names of the two products?

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Q4. When a solution of lead nitrate is added to a solution of sodium chloride, a white precipitate of lead chloride is produced.

(a) (i) Why is a precipitate formed?

...........................................................................................................................

........................................................................................................................... (1)

(ii) Complete and balance the equation for this precipitation reaction.

Pb+2

(aq) + Cl–

(aq) →

(3)

(b) Complete the table below by writing in the name and formula of the precipitate formed for each reaction. If there is no precipitate, write “no precipitate”.

(5)

(Total 9 marks)

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Q5. Sodium carbonate reacts with acids.

(i) Complete the word equation.

sodium carbonate + hydrochloric acid → sodium chloride + ...................... + water (1)

(ii) Name the salt produced if sodium carbonate reacts with dilute nitric acid.

........................................................................................................................... (1)

(Total 2 marks)

Q6. The diagrams show what happens when an acid is added to an alkali.

(a) What is present in the solution at stages 2 and 3 apart from universal indicator and water?

(i) At stage 2 .........................................................................................................

(ii) At stage 3.......................................................................................................... (3)

(b) Write an ionic equation to show how water is formed in this reaction and state the sources of the ions.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (3)

(Total 6 marks)

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Q7. The diagrams show what happens when an acid is added to an alkali.

(a) What is present in the flask at stage 2, besides universal indicator and water?

..................................................................................................................................... (1)

(b) Write an ionic equation to show how water is formed in this reaction and state the sources of the ions.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (3)

(Total 4 marks)

Q8. Read the passage carefully and then answer the questions.

From Chemistry Matters by Richard Hart, reproduced by permission of Oxford University Press

The electrolysis of acidified water

After a few drops of dilute sulphuric acid have been added to some distilled water, there will be three types of ion in solution:

from the water, H2O(l) → H+(aq) + OH–(aq)

from the acid, H2SO

4(aq) → 2H+(aq) + SO

4

2– (aq)

When the electrodes (anode and cathode) in a circuit are put into the acidified water, the hydroxide ions and the sulphate ions are both attracted to the electrode called the anode. However, it is harder for the sulphate ions to give up their electrons than for the hydroxide ions to do this. So the hydroxide ions are the ones which react and bubbles of oxygen are formed at the anode.

There are only hydrogen ions to be attracted towards the cathode and, when they get there, they take up electrons to form hydrogen molecules.

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Even in a small volume of water acidified with dilute sulphuric acid there will be billions of ions. Some will be anions and some will be cations.

(i) Name the ions in water acidified with dilute sulphuric acid.

..................................................................................................................................... (1)

(ii) Explain why only some of the ions are attracted to the anode.

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

(iii) Balance the equation for the reaction of hydroxide ions at the anode.

4OH– → H2O + O

2 + e–

(1) (Total 4 marks)

Q9. (a) Ammonium sulphate is made by the reaction:

2NH3(aq) + H

2SO

4(aq) →(NH

4)

2SO

4(aq)

(i) Complete the three answers in the table.

(3)

Question Answer

How many hydrogens are there in the formula of ammonium sulphate?

..............................................................

What is the name of the substance with the formula NH

3?

..............................................................

What is the name of the substance with the formula H

2SO

4?

..............................................................

(ii) What is the main use for ammonium sulphate?

........................................................................................................................... (1)

(iii) A similar reaction is used to make ammonium nitrate. What is the name of the acid which must be used?

........................................................................................................................... (1)

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(b) NH3 is made by the reversible reaction:

N2(g) + 3H

2(g) 2NH

3(g)

(i) Explain what the term reversible reaction means.

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (2)

(ii) What is the name of the raw material which is the source of nitrogen (N2)?

........................................................................................................................... (1)

(iii) Nitrogen is an element. Explain what the term element means.

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (2)

(Total 10 marks)

Q10. Ammonium nitrate and ammonium sulphate are used as fertilisers.

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(i) Which acid reacts with ammonia to form ammonium nitrate?

.................................................................................................................................... (1)

(ii) Which acid reacts with ammonia to form ammonium sulphate?

.................................................................................................................................... (1)

(iii) The reactions in (i) and (ii) are both exothermic. How can you tell that a reaction is exothermic?

....................................................................................................................................

.................................................................................................................................... (1)

(iv) The reactions in (i) and (ii) are both examples of acid + base reactions. What is the name of the chemical change which takes place in every acid + base reaction?

.................................................................................................................................... (1)

(Total 4 marks)

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Q11. The flow diagram shows how to make ammonia and nitric acid from the nitrogen in the air.

(a) A fertiliser is made by neutralising ammonia with nitric acid. What is the name of this fertiliser?

..................................................................................................................................... (1)

(b) In the flow diagram, why are two different catalysts used?

.....................................................................................................................................

..................................................................................................................................... (1)

(c) What happens to catalysts at the end of a reaction?

.....................................................................................................................................

..................................................................................................................................... (1)

(d) Explain why catalysts are used in many industrial chemical reactions.

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

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(e) Explain, in terms of collisions between molecules, why a high pressure is used in the reaction between nitrogen and hydrogen.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

(Total 7 marks)

Q12. The flow diagram shows some stages in the manufacture of the fertiliser ammonium nitrate (NH

4NO

3).

(a) The elements needed to make ammonia (NH3) are obtained from natural gas and air.

Which element is obtained from the air?

..................................................................................................................................... (1)

(b) The word equation for the formation of nitrogen monoxide is:

ammonia + oxygen → nitrogen monoxide + water

The platinum catalyst needs to be heated only at the start of the reaction. Suggest why.

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (1)

(c) Name the liquid A that reacts with nitrogen dioxide (NO2) to produce nitric acid (HNO

3).

..................................................................................................................................... (1)

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(d) Describe how ammonium nitrate (NH4NO

3) can be made from two of the products shown

in the flow diagram.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (2)

(Total 5 marks)

Q13. (a) Magnesium burns in oxygen, forming magnesium oxide.

This equation represents the reaction.

Mg (s) + O2 (g) → MgO (s)

(i) Balance the equation. (1)

(ii) Give the meaning of the state symbols (s) and (g).

(s) ..............................................

(g) .............................................. (2)

(b) Use the Formulae of Some Common Ions table on the Data Sheet to help you to answer this question.

Magnesium also reacts with chlorine to form magnesium chloride.

Give the formula of magnesium chloride .................................................................. (1)

(Total 4 marks)

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Q14. Use the Formulae of Some Common Ions table on the Data Sheet to help you to answer this question.

Acids react with alkalis to form salts and water.

Complete the table below by writing in the name and formula of the salt formed in each reaction.

The first one has been done for you.

(Total 4 marks)

Acid Alkali Salt Formula of salt

Hydrochloric acid Sodium hydroxide Sodium chloride NaCl

Nitric acid Sodium hydroxide

Sulphuric acid Potassium hydroxide

Q15. This item appeared in the Wolverhampton Express and Star on October 31st, 1997. Read the passage and answer the questions that follow.

Fumes scare at factory

Workers were forced to flee a factory after a chemical alert. The building was evacuated when a toxic gas filled the factory. It happened when nitric acid spilled on to the floor and mixed with magnesium metal powder.

(a) The equation which represents the reaction between magnesium and nitric acid is:

Mg(s)

+ 4HNO3(aq)

→ Mg(NO3)

2(aq) + 2H

2O

(1) + 2NO

2(g)

Give the formula of the toxic gas that was produced.

.................................................................................................................................... (1)

(b) Explain, in terms of particles, how the toxic gas was able to fill the factory quickly.

....................................................................................................................................

....................................................................................................................................

.................................................................................................................................... (2)

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(c) The reaction of nitric acid with magnesium metal powder is more dangerous than if the acid had fallen on to the same mass of magnesium bars. Explain why.

....................................................................................................................................

....................................................................................................................................

.................................................................................................................................... (1)

(d) (i) Water was sprayed on to the magnesium and nitric acid to slow down the reaction. Explain, in terms of particles, why the reaction would slow down.

..........................................................................................................................

..........................................................................................................................

.......................................................................................................................... (2)

(ii) Explain why it is better to add alkali, rather than just add water to the spillage.

..........................................................................................................................

.......................................................................................................................... (1)

(Total 7 marks)

Q16. (i) Which acid from the list should the student add to sodium hydroxide solution to make sodium sulphate?

ethanoic acid hydrochloric acid nitric acid sulphuric acid

..................................................................................................................................... (1)

(ii) When the acid was added to the alkali the beaker became warm. Name the type of reaction that releases heat.

..................................................................................................................................... (1)

(iii) Use the Data Sheet to help you to write the formula of sodium sulphate.

Formula: ..................................................................................................................... (1)

(Total 3 marks)

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Q17. Some drain cleaners contain a mixture of sodium hydroxide and powdered aluminium. When the mixture is poured into a drain it mixes with water and a chemical reaction takes place. The heat from the reaction helps to melt grease in the drain. Hydrogen gas is produced which stirs up the particles and helps to unclog the drain.

(a) Balance the equation for the reaction.

2Al(s)

+ ........ NaOH(aq)

+ ......... H2O → .........NaAl(OH)

4(aq) + 3H

2

(2)

(b) Why do the solid sodium hydroxide and aluminium powder not react when stored in a sealed container?

..................................................................................................................................... (1)

(c) Sodium hydroxide is a strong alkali and would react with any acids in the drain.

(i) Name the ion produced when any alkali is dissolved in water.

........................................................................................................................... (1)

(ii) Name the ion produced when any acid is dissolved in water.

........................................................................................................................... (1)

(iii) Name the compound formed when these ions react with each other.

........................................................................................................................... (1)

(Total 6 marks)

##

Sando-K is a medicine. It is given to people whose bodies contain too little of a particular element.

Sando-K is a mixture of two compounds. The formulae of the two compounds are given below.

KHCO KC1

(a) Which metal do people given Sando-K need?

..................................................................................................................................... (1)

(b) Sando-K contains the ion, CO . Which gas would be produced if a dilute acid was added to Sando-K? (The Data Sheet may help you to answer this question.)

..................................................................................................................................... (1)

3

32–

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(c) The compounds in Sando-K contain ions.

Complete the two sentences below.

Atoms change into positive ions by ....................................... one or more

............................................................. .

Atoms change into negative ions by ......................................... one or

more .................................................... . (4)

(d) Electricity can be used to show that an aqueous solution of Sando-K contains ions.

(i) Draw a diagram of an apparatus that you could use to prove that Sando-K contains ions.

(4)

(ii) Explain, as fully as you can, what would happen when the electricity is switched on.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (3)

(Total 13 marks)

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Q19. Sodium carbonate is a useful chemical that can be made from sodium chloride.

(a) The flow chart below shows one way in which sodium carbonate can be made.

(i) Write the formula of sodium carbonate. Use the Data Sheet to help you to answer this question.

........................................................................................................................... (1)

(ii) 1. Give one example of a thermal decomposition reaction shown in the flow chart.

................................................................................................................

................................................................................................................ (1)

2. Explain what is meant by a thermal decomposition reaction.

................................................................................................................

................................................................................................................ (2)

(iii) Name one substance that is recycled in this process.

........................................................................................................................... (1)

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(b) When sodium carbonate solution is added to zinc sulphate solution a white solid is precipitated.

(i) Use the Data Sheet to help you to name the white solid that is produced in this reaction.

........................................................................................................................... (1)

(ii) State why this solid is formed.

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (1)

(Total 7 marks)

Q20. (a) In an industrial process electricity is passed through a solution of sodium chloride in water. A student set up the apparatus shown below to investigate this process.

(i) Name gas X.

........................................................................................................................... (1)

(ii) Complete the half equation for the production of chlorine gas during the electrolysis.

............ Cl– → ............ e– → Cl2

(1)

(iii) The student found that the solution left in the cell was alkaline.

Which ion makes the solution alkaline?

........................................................................................................................... (1)

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(iv) Name the useful substance that can be obtained from the solution in the cell.

........................................................................................................................... (1)

(b) Sodium carbonate is another useful chemical that can be made from sodium chloride. The flow chart below shows one way in which sodium carbonate can be made.

(i) Write the formula of sodium carbonate. Use the Data Sheet to help you to answer this question.

........................................................................................................................... (1)

(ii) Salt is one raw material used in this process.

Name one other raw material used in this process.

........................................................................................................................... (1)

(iii) Sodium carbonate is one of the products of this process.

Name one other product.

........................................................................................................................... (1)

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(iv) 1. Give one example of a thermal decomposition reaction shown in the flow chart.

................................................................................................................

................................................................................................................ (1)

2. Explain what is meant by a thermal decomposition reaction.

................................................................................................................

................................................................................................................ (2)

(v) Name one substance that is recycled in this process.

........................................................................................................................... (1)

(c) When sodium carbonate solution is added to zinc sulphate solution a white solid is precipitated.

(i) Use the Data Sheet to help you to name the white solid that is produced in this reaction.

........................................................................................................................... (1)

(ii) State why this solid is formed.

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (1)

(Total 13 marks)

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Q21. (a) This label has been taken from a packet of Andrews Antacid.

(i) Write the simplest ionic equation which represents a neutralisation reaction.

........................................................................................................................... (1)

(ii) Chewing the tablet cures indigestion faster than swallowing the tablet whole. Explain why.

...........................................................................................................................

........................................................................................................................... (1)

(iii) Write the formula of the magnesium compound present in Andrews Antacid. You may find the Data Sheet helpful.

........................................................................................................................... (1)

(b) The active ingredients in the Antacid react with hydrochloric acid in the stomach to give salts, water and carbon dioxide.

A student investigated how quickly the tablets react with excess hydrochloric acid.

40 cm³ of dilute hydrochloric acid were placed in a conical flask. The flask was placed on a direct reading balance. Two Antacid tablets were quickly added to the flask. The apparatus was weighed immediately. At the same time, a stop clock was started. The mass was recorded every half minute for 5 minutes.

The results are shown in the table below.

The main active ingredient in Andrews Antacid is calcium carbonate.

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(i) Balance the equation which represents the reaction between calcium carbonate and hydrochloric acid.

CaCO3(s)

+ .......... HCl(aq)

→ CaCl2(aq)

+ H2O

(l) + CO

2(g)

(1)

(ii) State the meaning of the symbol “(aq)”.

........................................................................................................................... (1)

(iii) Why does the mass of the flask and contents decrease?

........................................................................................................................... (1)

(c) (i) Plot the results on the graph below and draw a smooth curve to show how the mass of the flask and its contents changes with time. Label this curve “A”.

(3)

(ii) One of the results does not appear to fit the pattern. Circle this result on the graph. (1)

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(d) The student did a second experiment. The only change was that the acid was twice as concentrated.

On the graph, sketch a second curve to show a possible result for this experiment. Label this curve “B”.

(2) (Total 12 marks)

Q22. Limestone (CaCO3) is a raw material. On strong heating it is converted to calcium oxide

which is a very useful substance.

(a) Calculate the formula mass (Mr) of calcium carbonate.

.....................................................................................................................................

Mr of calcium carbonate = ...............................................

(2)

(b) About 60 million tonnes of calcium oxide is made in Britain each year. Calculate the mass of calcium carbonate needed to make this amount of calcium oxide.

....................................................................................................................................

....................................................................................................................................

....................................................................................................................................

....................................................................................................................................

....................................................................................................................................

....................................................................................................................................

Mass of calcium carbonate needed = .............................. million tonnes (4)

(c) Water is added to some of the calcium oxide produced in a process known as ‘slaking’. The product of this reaction is used to make plaster.

CaO(s)

+ H2O

(1)→ Ca(OH)

2(s)

(i) Give the chemical name of Ca(OH)2.

.......................................................................................................................... (1)

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(ii) What is the physical state of the Ca(OH)2 formed in the reaction?

.......................................................................................................................... (1)

(Total 8 marks)

Q23. The salt sodium hydrogen phosphate (Na2HPO

4) is used as a softening agent in

processed cheese.

It can be made by reacting phosphoric acid (H3PO

4) with an alkali.

(a) Complete the name of an alkali that could react with phosphoric acid to make sodium hydrogen phosphate.

....................................... hydroxide (1)

(b) What is the name given to a reaction in which an acid reacts with an alkali to make a salt?

..................................................................................................................................... (1)

(c) How would the pH change when alkali is added to the phosphoric acid solution?

.....................................................................................................................................

..................................................................................................................................... (1)

(d) What ions are present when any acid is dissolved in water?

..................................................................................................................................... (1)

(e) What ions are present when any alkali is dissolved in water?

..................................................................................................................................... (1)

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(f) Write a chemical equation for the reaction which takes place between the ions you have named in (e) and (f).

..................................................................................................................................... (1)

(Total 6 marks)

Q24. Ammonia and nitric acid are both important chemicals. Nitric acid is made from ammonia.

The charts below show substances made from ammonia and nitric acid.

Substances made from Substances made from ammonia nitric acid

(a) Use the charts to help you answer these questions.

(i) What is the main use of both ammonia and nitric acid?

.......................................................................................................................... (1)

(ii) Work out the percentage of ammonia used to make nitric acid.

Percentage = ........................ % (1)

(iii) 100 million tonnes of ammonia are made in the world each year.

How much of this ammonia is used to make nylon?

.......................... million tonnes (1)

(b) The word equations below show how nitric acid is made.

1. nitrogen + hydrogen → ammonia

2. ammonia + oxygen → nitrogen monoxide + water

3. nitrogen monoxide + oxygen → nitrogen dioxide

4. nitrogen dioxide + water → nitric acid

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Use the word equations to help you answer these questions.

(i) From which two elements is ammonia made?

......................................................... and ......................................................... (1)

(ii) Name two of the raw materials needed to make nitric acid.

......................................................... and ......................................................... (2)

(c) A large amount of nitric acid is reacted with ammonia to make a fertiliser.

nitric acid + ammonia → fertiliser

(i) The reaction is a neutralisation reaction.

What type of chemical must ammonia be?

........................................................................................................................... (1)

(ii) Complete the chemical name for the fertiliser made from ammonia and nitric acid.

ammonium .................................................... (1)

(iii) The reaction of nitric acid with ammonia is exothermic.

Name the piece of equipment you could put into the solution to prove that the reaction is exothermic.

........................................................................................................................... (1)

(Total 9 marks)

Q25. This article appeared in a newspaper.

(a) The balanced chemical equation shows the reaction between steel and hydrochloric acid.

Fe(s) + 2HCl(aq) → FeCl2(aq) + H

2(g)

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(i) Which metal in steel reacted with the hydrochloric acid?

........................................................................................................................... (1)

(ii) The gas released was described as explosive. Explain why.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (3)

(b) In the factory hydrogen chloride is manufactured by reacting hydrogen with chlorine. Hydrochloric acid is formed when hydrogen chloride forms a solution in water.

(i) Water was sprayed on the steel and hydrochloric acid. This slowed the rate of reaction. Explain why.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (2)

(ii) It would have been better to neutralise the acid with an alkali rather than to just add water. Hydrochloric acid can be neutralised by reaction with sodium hydroxide. Complete the ionic equation for the neutralisation reaction.

(aq) + (aq) → H2O(l)

(2)

(iii) In the factory the acid leak was neutralised with slaked lime, Ca(OH)2, and not

sodium hydroxide, NaOH. Suggest why.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (2)

(Total 10 marks)

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Q26. Calcium tablets are taken to build and maintain strong bones and teeth.

(a) These tablets react with hydrochloric acid in the stomach.

CaCO3( ) + 2HCl(aq) → CaCl

2( ) + H

2O( ) + CO

2( )

(i) Add all these missing state symbols to the balanced chemical equation.

(2)

(ii) The calcium salt that is formed is absorbed during digestion. What is the name of the calcium salt?

...........................................................................................................................

........................................................................................................................... (1)

(b) The volume of carbon dioxide produced by one calcium tablet in the stomach can be found as shown.

The volume of carbon dioxide was recorded every 30 seconds until the reaction stopped.

Time in seconds 0 30 60 90 120 150 180 210 240

Volume of gas in cm3

0 24 36 46 52 56 59 60 60

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(i) Complete the graph of these results.

(3)

(ii) Describe one way in which this reaction can be made to go faster.

...........................................................................................................................

........................................................................................................................... (1)

(iii) A calculation, using the mass of this tablet, showed that 80 cm3 of carbon dioxide would be produced if the tablet was pure calcium carbonate. What do the results show about the purity of the tablet? Explain your answer by calculating the purity of this tablet.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (3)

(Total 10 marks)

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Q27. Many everyday substances can be classified as acids, bases or salts. For example, car batteries contain sulphuric acid, oven cleaners contain sodium hydroxide and table salt contains sodium chloride.

(a) A solution of each of these substances was tested with universal indicator.

Solution Colour of universal indicator

Sulphuric acid (H2SO

4) red

Sodium hydroxide (NaOH) purple

Sodium chloride (NaCl) green

(i) Explain how these universal indicator colours and the corresponding pH values could be used to identify each of these solutions.

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

...........................................................................................................................

........................................................................................................................... (3)

(ii) Name and give the formula of the ion which causes the solution to be acidic.

Name of ion ..................................................................................................

Formula of ion ................................................................................................. (2)

(b) Sodium chloride can be made by reacting sodium hydroxide with hydrochloric acid in the presence of an indicator.

(i) What is the name of this type of reaction?

.......................................................................................................................... (1)

(ii) Write a balanced chemical equation for this reaction.

..............(aq) + ..............(aq) → ..............(aq) + ..............(l) (2)

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(c) The atomic number for sodium is 11 and for chlorine is 17.

(i) Complete the diagrams to show the electron arrangements for a sodium atom and a chlorine atom.

(2)

(ii) These atoms form different particles by one electron transferring from the sodium atom to the chlorine atom. What is the name given to the particles formed?

........................................................................................................................... (1)

(iii) Why do these sodium and chloride particles bond?

...........................................................................................................................

........................................................................................................................... (1)

(d) Sodium chloride solution is electrolysed to form three products, hydrogen, chlorine and sodium hydroxide.

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Describe how each of these products are formed.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (3)

(Total 15 marks)

Q28. Acids and bases are commonly found around the home.

(a) Baking powder contains sodium hydrogencarbonate mixed with an acid.

(i) When water is added, the baking powder releases carbon dioxide. How could you test the gas to show that it is carbon dioxide?

Test ..................................................................................................................

Result of test .................................................................................................... (2)

(ii) Complete and balance the chemical equation for the reaction of sodium hydrogencarbonate with sulphuric acid.

NaHCO3 + H

2SO

4 → ....................... + ........................ + ..................

(2)

(b) Indigestion tablets contain bases which cure indigestion by neutralising excess stomach acid.

(i) One type of indigestion tablet contains magnesium hydroxide. This base neutralises stomach acid as shown by the balanced chemical equation.

Mg(OH)2 + 2HCl → MgCl

2 + 2H

2O

Write a balanced ionic equation for the neutralisation reaction.

.......................................................................................................................... (2)

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(ii) How does the pH in the stomach change after taking the tablets?

.......................................................................................................................... (1)

(c) Ammonium sulphate is used as a lawn fertiliser.

Using ammonia solution, describe how you would make the fertiliser ammonium sulphate.

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

.....................................................................................................................................

..................................................................................................................................... (3)

(Total 10 marks)

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Q29. A student investigated the electrolysis of lead bromide.

Lead bromide was placed in the tube and the circuit was switched on. The light bulb did not light up.

The tube was heated and soon the bulb lit up. The observations are shown in the table.

Positive electrode Negative electrode

red-brown gas silver liquid

(a) What is meant by electrolysis?

.................................................................................................................................... (2)

(b) Why did the lead bromide conduct electricity when the tube was heated?

.................................................................................................................................... (1)

(c) Name the substances formed at the:

positive electrode; .....................................................................................................

negative electrode. .................................................................................................... (2)

(d) Suggest one safety precaution that should be taken during this investigation.

.................................................................................................................................... (1)

(Total 6 marks)

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Q30. A student investigated the electrolysis of lead bromide.

Lead bromide was placed in the tube and the circuit was switched on. The light bulb did not light up.

The tube was heated and soon the bulb lit up. The observations are shown in the table.

Positive electrode Negative electrode

red-brown gas silver liquid

(a) What is meant by electrolysis?

.................................................................................................................................... (2)

(b) Why did the lead bromide conduct electricity when the tube was heated?

.................................................................................................................................... (1)

(c) Name the substances formed at the:

positive electrode; .....................................................................................................

negative electrode. .................................................................................................... (2)

(d) Suggest one safety precaution that should be taken during this investigation.

.................................................................................................................................... (1)

(Total 6 marks)

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M1. (a) oxygen / O2 (do not allow air)

for 1 mark 1

(b) idea that (it is a) catalyst / it increases the rate of reaction

for 1 mark 1

(c) water H2O and oxygen / O

2 (need both) (in either order)

for 1 mark 1

(d) ammonia / NH3 (do not allow ammonium)

(allow ammonium hydroxide / NH4OH or ammonia solution)

nitric acid / NHO3

in any order for 1 mark each 2

(e) 14 + 4 + 14 + 48 or Mr = 80

gains 1 mark

but or 35%

gains 2 marks 2

[7]

M2. (a) lead chloride } in any order potassium nitrate }

for 1 mark each 2

(b) lead chloride is solid / a precipitate potassium nitrate is aqueous / in solution / dissolves in water NOT liquid

for 1 mark each 2

(Accept ratio of molecular KNO3 : PbC1

2 is 2:1 for 2 marks)

(do not accept relative number of atoms in each compound)

One is a solid, one is a solution – worth 1 mark [4]

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M3. • correct use of react/reaction/reactants NOT mixed added to join/combine/displace NOT equals

• correct use of produce/products/gives/forms/makes/creates

• reactants correctly identified

• products correctly identified

(copper oxide reacts with sulphuric acid to produce copper sulphate and water, will be awarded all 4 marks)

for 1 mark each

Reactants must be correctly identified for ‘react’ mark to be given. Similarly for products [4]

M4. (a) (i) lead chloride/product of lead + chloride ions is insoluble (in water)

for 1 mark 1

(ii) Pb2+ + 2C1¯ → PbC12 *(s)

(allow (Pb)2+ 2 (C1–) )

formula solid state symbol balancing for 1 mark each

3

(b) copper hydroxide Cu(OH)2

each for 1 mark

lead sulphate PbSO4

each for 1 mark

no precipitate for 1 mark

Allow 1 mark for correct formula Na2SO

4 in (i)

Allow 1 mark for correct formula Mg (NO3)

2 in (ii)

0 marks for any formula in (iii) 5

[9]

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M5. (i) carbon dioxide (allow CO2)

for 1 mark 1

(ii) sodium nitrate (accept correct formula) for 1 mark

1 [2]

M6. (a) (i) sodium ions and chloride ions

(allow sodium chloride/salt) [not “chlorine”] for 1 mark 1

(ii) sodium ions and chloride ions (allow sodium chloride/salt) for 1 mark

H + ions (allow hydrochloric acid) for 1 mark

2

(b) H+ + OH– → H2O [N.B Na+ and Cl– may also be present]

H+ ions from acid

OH– ions from alkali

each for 1 mark

[N.B First mark lost if changes on ions not shown] 3

[6]

##

(a) sodium ions and chloride ions (not chlorine) allow sodium chloride/salt/common salt

for 1 mark 1

(b) H+ + OH– →H2O

H+ from (hydrochloric) acid

OH- from alkali/sodium hydroxide

lose 1 mark if no charge shown disregard other ions each for 1 mark

3 [4]

-

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M8. (i) hydrogen, hydroxide and sulphate

all three and no others any order do not credit any formula(e)

1

(ii) the anode is positive 1

(so) only the negative ions are attracted to it or (so) only the hydroxide ions and the sulphate ions are attracted (to it) or (so) only the anions are attracted (to it)

1

(iii) 2H2O + O

2 + 4e–

1 [4]

M9. (a) (i) 8

ammonia do not credit ammonium

sulphuric acid do not credit just sulphuric; credit sulfuric acid do not credit hydrogen sulphate

3

(ii) (as a) fertiliser 1

(iii) nitric (acid) accept HNO

3 if correct in every detail

1

(b) (i) chemical change (in which) or under suitable conditions

1

product(s) can be converted to reactant(s) or direction of reaction can be reversed or equilibrium can be achieved do not credit reaction can be reversed

1

(ii) air or (the) atmosphere

1

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(iii) made of atoms 1

which are all the same credit the idea that the particles (in an element) are all the same even if the name of the particles (the first mark) is incorrect or which have the same number of protons or which have the same atomic number / proton number it cannot be broken down into anything simpler (2) marks

1 [10]

M10. NOTE

In this question and throughout the Paper, if the name of a chemical is asked for, then the formula is acceptable only if it is correct in every detail. If the name is correct and the candidate has tried to be ‘helpful’ by giving, in addition, an incorrect version of the formula, then this is acceptable provided it does not lead to ambiguity.

(i) nitric (acid) accept HN0

3

1

(ii) sulphuric (acid) accept H

2SO

4

1

(iii) heat given out or temperature rise or energy given out or steam do not credit just ‘use a thermometer’ do not credit just 'change in temperature'

1

(iv) neutralisation accept neutralise accept neutral accept formation of salt or water do not credit exothermic

1 [4]

M11. (a) ammonium nitrate

accept NH4NO

3

do not accept ammonia nitrate 1

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(b) different reactions need different catalysts 1

(c) they are used over and over again accept they are reused accept they are not used up accept they are not changed recycling is neutral

1

(d) any two from

they speed up reactions

they reduce energy requirements accept allow reactions to take place at a lower temperature

they reduce costs accept make process more economic

2

(e) (high pressure) increases the frequency of collisions

accept more collisions move faster is neutral

1

this increases the rate of reaction accept ‘more successful collisions’ for 2 marks

1 [7]

M12. (a) nitrogen

accept N or N2

1

(b) the reaction is exothermic accept the reaction releases heat energy

1

(c) water accept H

2O or hydrogen oxide

1

(d) with ammonia and nitric acid 1

neutralisation accept a correct description of reacting (ammonia and nitric acid)

1 [5]

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M13. (a) (i) 2 Mg + O2 → 2 MgO

both 2s needed

allow O2 or any correct multiple

1

(ii) solid 1

gas 1

(b) MgCl2 / C1

2Mg

do not accept MG mg mG CL cl cL ignore charges

1 [4]

M14. sodium nitrate 1

NaNO

3

do not credit lower case N or O, upper case A 1

potassium sulphate 1

K2SO

4

accept potassium hydrogen sulphate or KHSO4

do not credit lower case K, S or O ignore charges on ions

1 [4]

M15. (a) NO2 / 2NO

2(g) / Nitrogen dioxide

for one mark 1

(b) particles of gas move / they move

reject spread out particles move randomly / mix / go between air molecules / diffusion

any two for 1 mark each 2

(c) faster reaction / more surface area (not smaller pieces) for one mark

1

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(d) (i) either lower temperature / particles move slower fewer collisions (owtte) / less energetic collisions / owtte or acid diluted (owtte) fewer collisions (owtte)

for 1 mark each 2

(ii) alkali neutralises the acid / stops the reaction or water will only slow the reaction not stop it

either for 1 mark 1

[7]

M16. (i) sulphuric acid / H2SO

4

accept sulfuric 1 for one mark 1

(ii) exothermic for one mark

1

(iii) Na2SO

4 / (Na)

2SO

4 / Na

2(SO

4) / (Na+)

2SO

4

2–

for one mark lower case O(Na

2SO

4) not accepted / tops of subscripted letters

should be in line or lower than lower case letters of symbols 1

[3]

##

(a) (2) : (6) : (2) All 3 correct gains 2 marks 2 correct gains 1 mark

2

(b) no water present/moist air cannot enter/do not thoroughly mix/ must be in solution etc.

for 1 mark 1

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(c) (i) hydroxide (ion) / OH–

for 1 mark 1

(ii) hydrogen (ion) / H+

for 1 mark 1

(iii) water/H2O/hydrogen oxide

for 1 mark 1

[6]

##

(a) potassium / K for 1 mark

1

(b) carbon dioxide / CO2

for 1 mark 1

(c) losing electrons gaining electrons

for 1 mark each 4

(d) (i) power supply, (not mains) beaker containing solution, (inert) electrodes and circuit ammeter or bulb/ (or see bubbling etc. at electrodes written by drawing)

for 1 mark each 4

(ii) reading on ammeter/bulb lights / (solution) conducts (electricity) bubbling / gas produced hydrogen produced chlorine / oxygen produced ions move to electrodes (must be linked to ions move) negative ions move to the positive electrode and/or positive ions move to the negative electrode negative ions lose electrons and/or positive ions gain electrons

any 3 for 1 mark each 3

[13]

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M19. (a) (i) Na2CO

3 or (Na+)

2 CO

3

2– must be completely correct

for 1 mark 1

(ii) (1) decomposition of limestone or decomposition of coal or decomposition of sodium hydrogen carbonate (owtte.) allow equations even if not correctly balanced

any 1 for 1 mark 1

(2) breakdown/split up not decomposed by heat

for 1 mark each 2

(iii) carbon dioxide or ammonia [CO2] or [NH

3]

for 1 mark 1

(b) (i) zinc carbonate or zinc hydroxide allow formulae if completely correct

for 1 mark 1

(ii) (zinc carbonate) is insoluble (in water) ((i) and (ii) are independent marks)

for 1 mark 1

[7]

M20. (a) (i) hydrogen/H2

for 1 mark 1

(ii) i.e. 2Cl¯ -2e– →Cl2

for 1 mark 1

(iii) hydroxide or OH–

for 1 mark 1

(iv) sodium hydroxide/caustic soda/NaOH/bleach/ chemical name of bleach

for 1 mark 1

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(b) (i) Na2CO

3 or (Na+)

2 CO

3

2–

for 1 mark 1

(ii) coal water/H

2O

limestone/CaCO3/calcium carbonate

any one for 1 mark 1

(iii) calcium chloride/CaCl2/sodium hydrogen

carbonate/NaHCO3

for 1 mark 1

(iv) decomposition/heating of limesstone decomposition/heating of coal decomposition/heating of sodium hydrogen carbonate

any 1 for 1 mark 1

described change e.g. NaHCO3 → Na

2 CO

3

(Use judgement) breakdown (owtte.) by heat

for 1 mark each 2

(v) carbon dioxide/CO2 or ammonia/NH

3

for 1 mark 1

(c) (i) zinc carbonate/ZnCO3/zinc

hydroxide/Zn(OH)2

for 1 mark 1

(ii) It is insoluble zinc carbonate is insoluble in water

for 1 mark 1

[13]

M21. (a) (i) H+ + OH- → H2 O/H

3O+ + OH- → 2H

2 O

for 1 mark 1

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(ii) 1 point from e.g. smaller bits bigger surface area faster reaction dissolve faster more particles open to attack by acid

any 1 for 1 mark 1

(iii) MgCO3 or MG2+CO

3

2- or CO3 Mg

for 1 mark 1

(b) (i) 2 HCl for 1 mark

1

(ii) aqueous/dissolved in water (not in solution) for 1 mark

1

(iii) CO2/gas evolved/gas has mass

for 1 mark 1

(c) (i) plotting points scales curve labelling axes including units

for 1 mark each 4

(d) faster same final mass

for 1 mark each 2

[12]

M22. (a) 40 + 12 + (3 × 16) = 100

each for 1 mark 2

(b) Mr of CaO = 56

for 1 mark

mass required = 60 × 100/56 for 2 marks

= 107.1 for 1 mark

4

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(c) (i) calcium hydroxide 1

(ii) solid 1

[8]

M23. (a) sodium 1

(b) neutralisation 1

(c) increase/inc. number 1

(d) H+

1

(e) OH–

1

(f) H+ + OH– → H2O

1 [6]

M24. (a) (i) fertilisers

for 1 mark 1

(ii) 7 for 1 mark

1

(iii) 5 for 1 mark (ignore other units)

1

(b) (i) both nitrogen and hydrogen for 1 mark

1

(ii) two of: nitrogen; hydrogen/methane/natural gas; oxygen/air; water; any fuel (allow symbols, do not allow nitrogen oxides)

any two for 1 mark each 2

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(c) (i) alkali/alkaline/base/basic for 1 mark

1

(ii) must be nitrate for 1 mark

1

(iii) thermometer or any other temperature measuring device for 1 mark

1 [9]

M25. (a) (i) iron must be named

do not accept Fe 1

(ii) hydrogen 1

and oxygen mixtures 1

burn rapidly 1

(b) (i) lowers concentration accept dilutes the acid do not accept cooling

1

less collisions (between particles) 1

(ii) H+ (aq)

accept H3O+ only if 2 in front of H

2O

1

OH− (aq)

if spectator ions correctly included on both sides, maximum = 1 mark

1

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(iii) Ca(OH2) weak alkali

accept NaOH strong alkali 1

Ca(OH)2 causes no problems

accept NaOH causes named problem (eg caustic or exothermic or burns or corrosive)

1 [10]

M26. (a) (i) (s) (aq) (1) (g)

2 or 3 correct 1 mark 1 correct 0 marks

2

(ii) calcium chloride 1

(b) (i) points deduct 1 mark for each error to a maximum of 2 marks

2

line accept a single line ‘best fit’ curve accept reasonable attempt at curve

1

(ii) increase temperature or heat

accept increase surface area or increase concentration or description

1

(iii) 75% or ¾ not pure 1 mark

only 60 cm3 (instead of 80 cm3 of gas)

or × 100 1 mark 3

[10]

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M27. (a) (i) H2SO

4 or red (acidic) pH < 7

accept names of compounds accept correct use of acidic

1

NaOH or purple (alkaline) pH > 7

alkaline and neutral without any mention of pH for 1 mark only 1

NaCl or green (neutral) pH 7

ignore high or low pH 1

(ii) hydrogen (ion) accept proton accept hydroxonium ion

1

H+

accept H3O+ for hydroxonium ion

1

(b) (i) neutralisation 1

(ii) NaOH + HCl ignore state symbols

1

NaCl + H2O

ignore state symbols maximum of 1 mark if incorrectly balanced

1

(c) (i) sodium – 2 . 8 . 1 accept 2.8.1 written

1

chlorine – 2 . 8 . 7 accept 2.8.7 written

1

(ii) ion(s) 1

(iii) attraction between oppositely charged particles (ions) accept attraction between + and – particles (ions) accept electrostatic attraction

1

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(d) chloride ions lose electrons to form chlorine

Cl– – e– → Cl 1

hydrogen ions gain electrons to form hydrogen

H+ + e– → H

1

sodium hydroxide remains in solution

Na + and OH– remain in solution to form sodium hydroxide

1 [15]

M28. (a) (i) test: limewater

accept calcium hydroxide solution 1

result: ‘goes’ cloudy accept white or milky do not accept misty or chalky test must be correct before result mark can be considered

1

(ii) 2 NaHCO3 + H

2SO

4 →

Na2SO

4 + (2) H

2O + (2) CO

2

1

correctly balanced 1

(b) (i) H+ + OH–

1

→ H2O

deduct one mark if incorrectly balanced

accept H3O+ instead of H+ then 2H

2O needed for balance

1

(ii) pH increases accept numerical indication

1

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(c) addition of sulphuric acid 1

correct use of an indicator accept idea of forming a neutral solution

1

crystallisation (of neutral solution) accept description using evaporation

1 [10]

M29. (a) breakdown / decomposition / splits into elements /

not ions

separates into elements / produce a chemical reaction 1

using electricity 1

(b) lead bromide melted / free ions

not electrolyte 1

(c) (+) bromine element must be appropriate to electrode

1

(–) lead element must be appropriate to electrode

1

(d) fume cupboard / protective clothing allow safety glasses not safety mat

1 [6]

M30. (a) breakdown / decomposition / splits into elements /

not ions

separates into elements / produce a chemical reaction 1

using electricity 1

(b) lead bromide melted / free ions

not electrolyte 1

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(c) (+) bromine element must be appropriate to electrode

1

(–) lead element must be appropriate to electrode

1

(d) fume cupboard / protective clothing allow safety glasses not safety mat

1 [6]

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