Explain, in terms of particles, how increasing the temperature and increasing the concentration of a reactant each increase the rate of a chemical reaction.
[6 marks]
Total for this question: 6
Chemistry extended-response trainer
AQA GCSE 8462
ORIGINAL
AQA GCSE Chemistry extended responses students lose most marks on — rates, electrolysis, crude oil, reactivity and water treatment. Plan the answer, mark it against the level descriptors, then read a model response.
Board and spec code confirmed against AQA 8462 · registry checked 2026-07-17How this checking works
How to use it: write your full answer first, then reveal the mark scheme and tick the points you made. AQA marks these by level — a detailed, linked answer — not by counting points, so the tick count is only a rough guide. Read the model answer to see what a Level 3 looks like.
Q1
The rate and extent of chemical change
Explain
Write your full answer first — then mark it.
Q2
Chemical changes - electrolysis
Explain
Concentrated sodium chloride solution (brine) is electrolysed using inert electrodes. Explain, with reference to the ions present, which product forms at each electrode, and name the other product left in the solution.
[6 marks]
Total for this question: 6
Write your full answer first — then mark it.
Q3
Organic chemistry - crude oil
Describe and explain
Crude oil is separated into useful fractions by fractional distillation. Describe how the process separates the crude oil, and explain why the hydrocarbons end up in different fractions.
[6 marks]
Total for this question: 6
Write your full answer first — then mark it.
Q4
The periodic table - Group 1
Describe and explain
Lithium, sodium and potassium all react with water. Describe what you would observe as each metal reacts, and explain why reactivity increases down Group 1.
[6 marks]
Total for this question: 6
Write your full answer first — then mark it.
Q5
Using resources - potable water
Explain
Explain how potable water is produced from a fresh water source such as a reservoir, and explain why producing potable water from sea water needs a different and more expensive process.
[6 marks]
Total for this question: 6
Write your full answer first — then mark it.
Q6
Bonding - diamond and graphite
Compare and explain
Diamond and graphite are both made only of carbon. Compare their structures and explain why both have high melting points, why diamond is hard, why graphite is soft, and why only graphite conducts electricity.
[6 marks]
Total for this question: 6
Write your full answer first — then mark it.
Q7
Bonding - ionic compounds and small molecules
Compare and explain
Sodium chloride has a much higher melting point than methane. Molten sodium chloride conducts electricity, but solid sodium chloride and both solid and liquid methane do not. Compare and explain these properties in terms of structure, bonding and particles.
[6 marks]
Total for this question: 6
Write your full answer first — then mark it.
Q8
Bonding - metals and alloys
Explain
Explain, in terms of structure and bonding, why a pure metal conducts electricity and can be bent into shape, and why an alloy is usually harder than the pure metal.
[6 marks]
Total for this question: 6
Write your full answer first — then mark it.
Q9
Quantitative chemistry - reacting masses and percentage yield (Higher tier)
Calculate and explain
Higher tier
Calcium carbonate decomposes when heated: CaCO3(s) → CaO(s) + CO2(g). A student heats 25.0 g of calcium carbonate and obtains 11.2 g of calcium oxide. Use Mr(CaCO3) = 100 and Mr(CaO) = 56. Calculate the theoretical mass of calcium oxide, calculate the percentage yield, and explain two reasons why the yield could be less than 100%.
[6 marks]
Total for this question: 6
Write your full answer first — then mark it.
Q10
Chemical changes - preparing a soluble salt
Describe
Describe how to prepare a pure, dry sample of copper sulfate crystals from copper oxide and dilute sulfuric acid. Give the purpose of the important stages in the method.
[6 marks]
Total for this question: 6
Write your full answer first — then mark it.
Q11
Energy changes - bond energies and reaction profiles (Higher tier)
Calculate and explain
Higher tier
Hydrogen reacts with chlorine: H2 + Cl2 → 2HCl. The bond energies are H-H = 436, Cl-Cl = 243 and H-Cl = 431 kJ/mol. Calculate the overall energy change and explain what a reaction profile would show, including the effect of a catalyst.
[6 marks]
Total for this question: 6
Write your full answer first — then mark it.
Q12
Rates of reaction - surface area practical
Describe and explain
A student investigates how the surface area of marble chips affects their rate of reaction with excess hydrochloric acid. Describe a method that produces valid results and explain the expected results using collision theory.
[6 marks]
Total for this question: 6
Write your full answer first — then mark it.
Q13
Chemical analysis - paper chromatography
Describe, calculate and explain
A student compares a black food colouring B with pure reference dyes X and Y using paper chromatography. The solvent front moves 8.0 cm from the pencil origin line. Measured from that line, X gives one spot at 2.0 cm, Y gives one spot at 6.0 cm, and B gives spots at 2.0 cm, 4.0 cm and 6.0 cm. Describe how to produce the chromatogram, calculate the Rf values, and explain what the results show about B.
[6 marks]
Total for this question: 6
Write your full answer first — then mark it.
Q14
Chemistry of the atmosphere - development of the atmosphere
Describe and explain
Describe and explain how the Earth's atmosphere is thought to have changed from its early atmosphere to the present atmosphere. Include the changes in water vapour, carbon dioxide and oxygen.
[6 marks]
Total for this question: 6
Write your full answer first — then mark it.
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