1
1 Sodium burns in air to form sodium oxide, Na2O.
(a) State the colour of the flame seen when sodium burns.
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(b) Write a chemical equation for the reaction which takes place when sodium burns in air to form
sodium oxide.
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[Total: 3]
2 When NaOH(aq) is added to aqueous iron(III) chloride, FeCl3(aq), a solid product is formed.
(a) State the colour of this solid product.
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(b) Name this solid product.
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[Total: 2]
3 A student prepares magnesium sulfate crystals, MgSO4, by adding excess magnesium to dilute
sulfuric acid.
Describe two observations which show the reaction has finished.
1 ...............................................................................................................................................
2 ............................................................................................................................................... [2]
[Total: 2]
4 When potassium is added to water, it reacts vigorously and a coloured flame is seen.
The equation for the reaction is shown.
2K(s) + 2H2O(l) → 2KOH(aq) + H2(g)
The solution formed is potassium hydroxide, a strong alkali.
(a) State the formula of the ion responsible for alkalinity in a solution.
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(b) State the colour of litmus in a strong alkali.
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[Total: 2]
2
5 Aqueous potassium hydroxide reacts with a dilute acid to produce aqueous
potassium chloride, KCl(aq), which is a salt.
(a) Name the dilute acid used.
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(b) State the type of reaction taking place.
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(c) Name the experimental technique used when salts are made by reacting a dilute acid with an
aqueous alkali.
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[Total: 3]
6 When aqueous silver nitrate, AgNO3(aq), is added to aqueous potassium chloride, a precipitate is
formed.
(a) State the colour of the precipitate formed.
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(b) Name the precipitate formed.
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(c) Write the ionic equation for the reaction. Include state symbols.
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[Total: 5]
7 A student prepares magnesium sulfate crystals, MgSO4, by adding excess magnesium to dilute
sulfuric acid.
The aqueous magnesium sulfate is heated until crystals begin to appear.
(a) Suggest the name for a solution in which no more solute can dissolve.
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(b) Suggest why more crystals of magnesium sulfate appear on cooling.
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[Total: 2]
8 + +
Aqueous potassium hydrogensulfate, KHSO4(aq), contains the ions K (aq), H (aq) and SO4 (aq).
(a) Describe the observations in the following tests.
3
(i) A flame test is carried out on aqueous potassium hydrogensulfate.
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(ii) Solid copper(II) carbonate is added to aqueous potassium hydrogensulfate.
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2+
(iii) An acidic solution containing aqueous barium ions, Ba (aq), is added to aqueous
potassium hydrogensulfate.
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(b) Write the ionic equation for the reaction in (a)(iii).
Include state symbols.
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[Total: 7]
9 A student prepares calcium nitrate, Ca(NO3)2, by adding calcium carbonate to dilute nitric acid.
(a) Write the chemical equation for this reaction.
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(b) Describe two observations during this reaction.
1 ........................................................................................................................................
2 ........................................................................................................................................ [2]
[Total: 4]
10 A student prepares calcium nitrate, Ca(NO3)2, by adding calcium carbonate to dilute nitric acid.
The student continues to add calcium carbonate until it is in excess.
The student then removes the excess calcium carbonate by filtration and collects the aqueous
calcium nitrate.
The student gently heats the aqueous calcium nitrate until the solution is saturated.
(a) Suggest what is meant by the term saturated solution.
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........................................................................................................................................... [2]
4
(b) Describe how crystals are produced from a hot saturated solution.
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[Total: 3]
11 The formula for crystals of hydrated copper(II) sulfate is CuSO4•5H2O.
Hydrated copper(II) sulfate is made by reacting copper(II) oxide with dilute sulfuric acid.
The overall equation is shown.
CuO + H2SO4 + 4H2O → CuSO4•5H2O
The crystals are made using the following steps:
3 3
step 1 50.0 cm of 0.200 mol / dm dilute sulfuric acid is heated in a beaker. Powdered copper(II)
oxide is added until the copper(II) oxide is in excess. Aqueous copper(II) sulfate is formed.
step 2 The excess copper(II) oxide is separated from the aqueous copper(II) sulfate.
step 3 The aqueous copper(II) sulfate is heated until a saturated solution is formed.
step 4 The saturated solution is allowed to cool and crystallise.
step 5 The crystals are removed and dried.
(a) State one observation that indicates the copper(II) oxide is in excess in step 1.
........................................................................................................................................... [1]
(b) Step 1 is repeated without heating the dilute sulfuric acid.
All other conditions are kept the same.
The rate of reaction decreases.
Give a reason why the rate of reaction decreases.
Explain your answer in terms of particles.
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5
(c) Name a substance, other than copper(II) oxide, that can be added to dilute sulfuric acid to
produce copper(II) sulfate in step 1.
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(d) Name the process used to separate excess copper(II) oxide from aqueous copper(II) sulfate
in step 2.
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(e) Suggest what is meant by the term saturated solution in step 3.
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(f) The phrase ‘heating to dryness’ means heating until no more water is given off.
Explain why aqueous copper(II) sulfate is not heated to dryness in step 3.
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[Total: 9]
12 Ammonia and hydrazine are weak bases.
The chemical equation for the reaction between one molecule of ammonia and one molecule of
water is shown.
+ −
NH3 + H2O ⇌ NH4 + OH
(a) State the meaning of the term base.
........................................................................................................................................... [1]
(b) Write a chemical equation for the reaction between one molecule of hydrazine, N2H4, and one
molecule of water.
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[Total: 2]
13 A student determines the concentration of a solution of dilute sulfuric acid, H2SO4, by titration with
aqueous sodium hydroxide, NaOH.
3 3
step 1 25.0 cm of 0.200 mol / dm NaOH is transferred to a conical flask.
step 2 Three drops of methyl orange indicator are added to the conical flask.
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step 3 A burette is filled with H2SO4.
step 4 The acid in the burette is added to the conical flask until the indicator changes colour. The
volume of acid is recorded. This process is known as titration.
step 5 The titration is repeated several times until a suitable number of results is obtained.
3 3
(a) Name the piece of apparatus used to measure exactly 25.0 cm of 0.200 mol / dm NaOH in
step 1.
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(b) State the colour change of the methyl orange indicator in step 4.
from ................................................................ to ................................................................
[1]
(c) State how the student decides that a suitable number of results have been obtained.
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[Total: 3]
14 Zinc sulfate crystals, ZnSO4•7H2O, are hydrated.
Zinc sulfate crystals are made by reacting zinc carbonate with dilute sulfuric acid.
The equation for the overall process is shown.
ZnCO3 + H2SO4 + 6H2O → ZnSO4•7H2O + CO2
step 1 Large pieces of solid zinc carbonate are added to dilute sulfuric acid until the zinc carbonate
is in excess. This forms aqueous zinc sulfate.
step 2 The excess zinc carbonate is separated from the aqueous zinc sulfate.
step 3 The aqueous zinc sulfate is heated until a saturated solution is formed.
step 4 The saturated solution is allowed to cool and crystallise.
step 5 The crystals are removed and dried.
(a) In step 1, zinc carbonate is in excess when no more zinc carbonate dissolves.
State one other observation that indicates the zinc carbonate is in excess in step 1.
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(b) Name a different substance, other than zinc carbonate, that can be added to dilute sulfuric
acid to produce aqueous zinc sulfate in step 1.
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(c) Step 1 is repeated using powdered zinc carbonate instead of large pieces.
All other conditions are kept the same.
The rate of reaction increases.
Give a reason why the rate of reaction increases. Explain your answer in terms of particles.
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(d) Suggest what is observed when the solution is saturated in step 3.
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(e) The formula of zinc sufate crystals is ZnSO4•7H2O.
Give the formula of the solid formed if the crystals are heated to dryness in step 3.
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[Total: 6]
15 Calcium hydroxide, Ca(OH)2, is slightly soluble in water.
Limewater is a saturated solution of calcium hydroxide, Ca(OH)2(aq).
(a) Name the gas limewater is used to test for.
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(b) Suggest what is meant by the term saturated solution.
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(c) Describe how you would make a sample of limewater starting with solid calcium hydroxide.
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(d) Describe how you would test for the presence of calcium ions in a sample of limewater.
test ....................................................................................................................................
observations .....................................................................................................................
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[Total: 8]
