Rates of reaction test with answers for GCSE chemistry (free PDF download)

Quick answer: The rate of reaction is how quickly reactants are used up or products form, measured as amount per unit time. This Chemistry 9-10 test on rates of reaction has 8 questions worth 20 marks, to do in 45 minutes: concentration and collisions, two experiments and mean rate. The mark scheme is on a separate page; free printable PDF.

This test lasts 45 minutes and is worth 20 marks. Answer every question. In explanations, refer to particles, collisions and activation energy. Show every step of a calculation and give units, such as cm³/s.

Level: Chemistry grades 9-10 (GCSE · IGCSE · O Level · Class 9-10) · Curriculum: HS-PS1-5

Time: 45 minutes · 8 questions · Total: 20 marks · Calculator allowed

Contents

Question 1 Concentration and collisions (3 marks)

Zinc reacts faster with 2.0 mol/dm³ hydrochloric acid than with 1.0 mol/dm³ acid.

Explain the difference in terms of particles. (2 marks)
State the effect on the final volume of hydrogen if the same mass of zinc is used in excess acid. (1 mark)

Question 2 Two experiments (3 marks)

The figure shows gas collected in experiments A and B.

State which experiment is faster. (1 mark)
Explain why both reach 30 cm³. (1 mark)
Suggest one change that would make B slower than A. (1 mark)

Gas volume for experiments A and B.

Question 3 Mean rate (2 marks)

A reaction produces 54 cm³ of gas in 45 s. Calculate the mean rate in cm³/s. (2 marks)

Question 4 Surface area (3 marks)

Emma cuts a cube of marble of side 4 cm into eight cubes of side 2 cm.

Calculate the total surface area before and after cutting. (2 marks)
State how the cutting changes the rate of reaction with acid. (1 mark)

Question 5 Temperature (3 marks)

Warming a reaction mixture increases the rate.

Give two reasons in terms of particles. (2 marks)
State which reason is more important. (1 mark)

Question 6 Catalysts (2 marks)

Explain what a catalyst does and why it is not used up. (2 marks)

Question 7 Doubling rule (2 marks)

A reaction takes 120 s at 25 °C. The rate doubles for every 10 °C rise. Calculate the time at 45 °C. (2 marks)

Question 8 Flour dust (2 marks)

A cloud of flour dust in a mill can explode, but a heap of flour only burns slowly. Explain why. (2 marks)

What is the rate of reaction? — Amount of product formed or reactant used per time

What does collision theory say? — Particles must collide with enough energy to react

Name the four main factors that change rate. — Temperature, concentration, surface area, catalyst

Why does powder react faster than lumps? — Larger surface area, more collisions

What is a catalyst? — A substance that speeds up a reaction and is not used up

How does a catalyst work? — Lowers the activation energy

Unit of rate for a gas volume? — cm³/s

Effect of raising pressure on a gas reaction? — More particles per volume, higher rate

What is shown by the gradient of a graph? — The rate of reaction

Why does the curve flatten? — Reactants have been used up