Rates of reaction: Edexcel International GCSE Chemistry questions

Every Edexcel International GCSE Chemistry exam question on Rates of reaction (specification points 3.9–3.16), 2019–2025, with its mark scheme and examiner’s report.

All 142 questions on Rates of reaction, as a list

June 2025, Paper 2, Q2(c) (2 marks): Draw a sketch graph to show how the volume of hydrogen changes with time until the reaction has finished. (2) Volume 0 Time
June 2025, Paper 2, Q2(d) (4 marks): Explain why increasing the temperature of the hydrochloric acid affects the rate of the reaction. Refer to collision theory in your answer. (4)
June 2025 (R), Paper 1, Q3(b) (2 marks): The experiment is repeated with the water at a higher temperature. Explain, in terms of particles, why the copper(II) hydroxide takes less time to form. (2)
June 2025 (R), Paper 1, Q7(b)(i) (1 mark): Plot the student’s results. The first three have been plotted for you. (1)
June 2025 (R), Paper 1, Q7(b)(ii) (1 mark): Draw a curve of best fit through the points. (1) 2.0 1.8 1.6 1.4 1.2 Total mass of 1.0 CO2 produced in grams 0.8 0.6 0.4 0.2 0 0 1 2 3 4 5 6 7 8 Time in minutes
June 2025 (R), Paper 1, Q7(b)(iii) (3 marks): Calculate the rate of reaction at 2 minutes by drawing a tangent to the curve and calculating the gradient of the tangent. Give the units for the rate of reacti
June 2025 (R), Paper 1, Q7(b)(iv) (4 marks): Explain why the shape of the graph changes during the 8 minutes. (4)
June 2025 (R), Paper 1, Q7(c) (3 marks): The student repeats the experiment using the same mass of calcium carbonate but as powder rather than chips, keeping all other conditions the same. Explain the
November 2024, Paper 1, Q5(b) (2 marks): The rate of reaction is increased by adding a suitable catalyst. Describe how a catalyst increases the rate of a reaction. (2)
November 2024, Paper 1, Q5(c)(i) (2 marks): Name the pieces of apparatus labelled A and B. (2) A B
November 2024, Paper 1, Q5(c)(ii) (2 marks): Determine the volume of oxygen gas produced in the first 4 minutes. Show on the graph how you obtain your answer. (2) volume of oxygen = cm3
November 2024, Paper 1, Q5(c)(iii) (4 marks): Determine the rate of reaction at 8 minutes by drawing a suitable tangent to the curve. Include the units for the rate of reaction. (4) rate of reaction = units
November 2024, Paper 1, Q8(a) (1 mark): Give a reason why the reading on the balance decreases during the reaction. (1)
November 2024, Paper 1, Q8(b) (2 marks): Explain why the rate of reaction is greatest at the start. (2)
November 2024, Paper 1, Q8(c) (1 mark): After 10 minutes, the reaction stops even though there are marble chips remaining. Give a reason why the reaction stops. (1)
November 2024, Paper 1, Q8(d)(i) (2 marks): Give two variables that should be controlled to make sure the results are valid. (2) 1 2
November 2024, Paper 1, Q8(d)(ii) (3 marks): Explain the effect of increasing the temperature of hydrochloric acid on the rate of reaction. (3)
June 2024, Paper 1, Q9(a)(i) (1 mark): State why mass is lost from the flask. (1)
June 2024, Paper 1, Q9(a)(ii) (1 mark): State the purpose of the cotton wool. (1)
June 2024, Paper 1, Q9(b)(i) (4 marks): Explain the shape of the graph. You should assume that the marble chips are in excess. (4)
June 2024, Paper 1, Q9(b)(ii) (2 marks): On the grid, draw the curve you would expect to obtain if the student uses the same volume of hydrochloric acid but with half the concentration. Assume that all
June 2024, Paper 1, Q9(c) (3 marks): The student repeats the experiment using the same mass of smaller marble chips. Explain, using particle collision theory, how using smaller marble chips would a
June 2024 (R), Paper 1, Q7(a)(i) (1 mark): Name a suitable piece of apparatus to measure the volume of sulfuric acid. (1)
June 2024 (R), Paper 1, Q7(a)(ii) (1 mark): Give a reason why the mass of zinc pieces does not need to be measured accurately. (1)
June 2024 (R), Paper 1, Q7(a)(iii) (1 mark): Give a reason why the student quickly connects the gas syringe in step 3. (1)
June 2024 (R), Paper 1, Q7(a)(iv) (1 mark): State how the student would know when the reaction stops. (1)
June 2024 (R), Paper 1, Q7(b)(i) (3 marks): A tangent to the curve has been drawn at a time of 80 s. Use the tangent to calculate the rate of reaction at 80 s. Show your working on the graph. Give the uni
June 2024 (R), Paper 1, Q7(b)(ii) (6 marks): Explain the shape of the graph in these regions. (6) from 0 s to 60 s from 60 s to 150 s from 150 s to 240 s
June 2024 (R), Paper 1, Q10(a) (2 marks): Describe how a catalyst increases the rate of a reaction. (2)
June 2024 (R), Paper 1, Q10(b)(i) (1 mark): Name the glass container the student uses. (1)
June 2024 (R), Paper 1, Q10(b)(ii) (3 marks): The student waits until the hydrogen peroxide solution completely decomposes. Describe how the student could then show that the manganese(IV) oxide was a cataly
June 2024 (R), Paper 2, Q3(c)(i) (1 mark): Give a reason why the student uses magnesium powder rather than magnesium ribbon. (1)
November 2023, Paper 1, Q6(c)(i) (1 mark): Plot the student’s results on the grid. (1)
November 2023, Paper 1, Q6(c)(ii) (1 mark): Draw a curve of best fit. (1) 100 80 60 Volume of oxygen in cm3 40 20 0 0 20 40 60 80 100 120 140 160 Time in seconds
November 2023, Paper 1, Q6(d)(i) (3 marks): Explain in terms of particle collision theory how decreasing the concentration affects the rate of a reaction. (3)
November 2023, Paper 1, Q6(d)(ii) (2 marks): The student repeats the experiment using the same volume of hydrogen peroxide solution but with half the original concentration. All other conditions are kept t
November 2023, Paper 1, Q6(e) (2 marks): In this reaction, the manganese(IV) oxide acts as a catalyst. Explain how a catalyst works. (2)
June 2023, Paper 1, Q10(a)(ii) (2 marks): The volume of hydrogen collected is measured at regular time intervals. Curve A shows the results of this experiment. 40 A 30 Volume of hydrogen in cm3 20 10 0
June 2023, Paper 1, Q10(b)(i) (4 marks): In one of these experiments the student repeats the original method but at a temperature of 20 °C. Explain in terms of particle collision theory why the curve o
June 2023, Paper 1, Q10(b)(ii) (2 marks): In the other experiment the student repeats the original method but uses 20 cm3 of hydrochloric acid containing 0.0018 mol. Explain why curve C shows the result
June 2023, Paper 1, Q10(c) (2 marks): Catalysts can be used to speed up reactions. Describe how a catalyst works. (2)
June 2023 (R), Paper 1, Q6(a) (1 mark): Give a reason why the gas that collects in the gas syringe is not pure oxygen. (1)
June 2023 (R), Paper 1, Q6(b) (2 marks): The rate of reaction can be increased by adding a catalyst to the hydrogen peroxide solution. Describe how a catalyst increases the rate of a reaction. (2)
June 2023 (R), Paper 1, Q6(c) (5 marks): These solids catalyse the decomposition of hydrogen peroxide solution. • lead(IV) oxide • manganese(IV) oxide Describe a method that the student could use to fi
June 2023 (R), Paper 1, Q6(d) (2 marks): A student investigates the decomposition of a solution of hydrogen peroxide at different temperatures. The graph shows how the total volume of oxygen collected
January 2023, Paper 1, Q11(b) (3 marks): The student repeats the experiment and records the volume of hydrogen gas collected. The graph shows the student’s results. 300 250 200 Volume of hydrogen in cm
January 2023, Paper 2, Q6(c)(i) (1 mark): Give a reason why the number of moles of concentrated sulfuric acid does not change. (1)
January 2023 (R), Paper 1, Q4(a) (2 marks): Give two variables that the student needs to keep constant in this investigation. (2) 1 2
January 2023 (R), Paper 1, Q4(b)(i) (1 mark): Plot the student’s results on the grid. (1)
January 2023 (R), Paper 1, Q4(b)(ii) (1 mark): Draw a circle around the anomalous result. (1)
January 2023 (R), Paper 1, Q4(b)(iii) (1 mark): Draw a curve of best fit. (1) 180 170 160 150 Time taken in seconds 140 130 120 110 10 20 30 40 50 60 70 Temperature in °C
January 2023 (R), Paper 1, Q4(b)(iv) (1 mark): Give a reason for the anomalous result. (1)
January 2023 (R), Paper 1, Q4(b)(v) (2 marks): Use your graph to determine the time taken for the mixture to turn blue at 55 °C. Show your working on the graph. (2) time taken = s
January 2023 (R), Paper 1, Q4(c) (2 marks): Use information from the table to calculate the mean rate of reaction at 20 °C. Use the expression 1 = mean rate time in seconds Give your answer in standard fo
January 2023 (R), Paper 1, Q4(d) (3 marks): Explain how increasing the temperature affects the rate of a reaction. Refer to particle collision theory in your answer. (3)
June 2022, Paper 1, Q4(a)(iv) (2 marks): Explain the advantage of using iron powder rather than pieces of iron. (2)
June 2022, Paper 1, Q6(b)(i) (1 mark): Plot the student’s results. (1)
June 2022, Paper 1, Q6(b)(ii) (1 mark): Draw a curve of best fit. (1) 100 80 60 Volume of hydrogen in cm3 40 20 0 0 20 40 60 80 Time in s
June 2022, Paper 1, Q6(b)(iii) (2 marks): Determine the volume of hydrogen collected in the first 10 seconds. Show on the graph how you obtained your answer. (2) volume of hydrogen = cm3
June 2022, Paper 1, Q6(b)(iv) (2 marks): Explain why the rate of reaction is greatest at the start of the reaction. (2)
June 2022, Paper 1, Q6(c)(i) (2 marks): On the grid, draw the curve you would expect the student to obtain. (2)
June 2022, Paper 1, Q6(c)(ii) (3 marks): Explain, in terms of particle collision theory, how increasing the temperature affects the rate of reaction. (3)
June 2022 (R), Paper 1, Q9(a)(i) (2 marks): Explain which is the best catalyst for the reaction. (2)
June 2022 (R), Paper 1, Q9(a)(ii) (2 marks): Explain how a catalyst increases the rate of a reaction. (2)
June 2022 (R), Paper 1, Q9(b)(i) (4 marks): Explain, using the particle collision theory, how increasing the temperature affects the rate of a reaction. (4)
June 2022 (R), Paper 1, Q9(b)(ii) (2 marks): Explain why using a solution of a lower concentration decreases the rate of reaction. (2)
June 2022 (R), Paper 2, Q7(a)(ii) (1 mark): Give the reason for using a catalyst. (1)
January 2022, Paper 1, Q9(a) (2 marks): Explain why using a cotton wool plug increases the accuracy of the student’s results. (2)
January 2022, Paper 1, Q9(c)(ii) (1 mark): State how the student would know when the reaction has stopped. (1)
January 2022, Paper 1, Q9(c)(iv) (3 marks): Use the graph to calculate the rate of reaction, in grams per second, at time 60 seconds. Show your working on the graph. (3) rate of reaction = g / s
January 2022, Paper 1, Q9(d)(i) (2 marks): Describe the relationship between the initial rate of reaction and percentage concentration of the original hydrochloric acid. (2)
January 2022, Paper 1, Q9(d)(ii) (2 marks): Explain why changing the concentration of hydrochloric acid has an effect on the initial rate of reaction. (2)
January 2022, Paper 2, Q5(a) (5 marks): Three different solids are catalysts for the decomposition of hydrogen peroxide solution. A student is given hydrogen peroxide solution and a sample of each of
January 2022, Paper 2, Q5(b)(ii) (1 mark): On the diagram, draw a curve to show the reaction profile for the same reaction when a catalyst is used. (1)
January 2022 (R), Paper 1, Q8(b)(i) (1 mark): Plot the student’s results. The first three have been done for you. (1)
January 2022 (R), Paper 1, Q8(b)(ii) (1 mark): Draw a circle around the anomalous result. (1)
January 2022 (R), Paper 1, Q8(b)(iii) (1 mark): Draw a curve of best fit. (1) 240 220 200 180 160 140 120 100 80 60 40 20 0 0 2 4 6 8 10 12 14 16 Time in minutes
January 2022 (R), Paper 1, Q8(b)(iv) (1 mark): Give a possible reason for the anomalous result. (1)
January 2022 (R), Paper 1, Q8(b)(v) (1 mark): Determine a more likely value for this result. (1)
January 2022 (R), Paper 1, Q8(c)(i) (2 marks): Explain how the shape of the curve shows how the rate of the reaction changes as time increases. (2)
January 2022 (R), Paper 1, Q8(d) (3 marks): The student does another experiment using • the same amount of similarly sized magnesium granules instead of zinc • the same volume of sulfuric acid, but of a l
January 2022 (R), Paper 1, Q8(e) (3 marks): Explain, in terms of particle collision theory, how increasing the temperature affects the rate of a reaction. (3)
January 2022 (R), Paper 2, Q5(b)(i) (2 marks): A catalyst is used in this reaction. Explain how a catalyst increases the rate of a reaction. (2)
November 2021, Paper 1, Q5(c)(ii) (1 mark): Suggest why the teacher uses copper powder instead of the same mass of large pieces of copper. (1)
November 2021, Paper 1, Q7(a)(ii) (1 mark): Give a reason why this reaction only occurs at high temperatures. (1)
November 2021, Paper 1, Q7(b)(i) (2 marks): The rate of the reaction is increased by passing the gases over a catalyst. Explain how a catalyst increases the rate of a reaction. (2)
November 2021, Paper 1, Q7(b)(ii) (3 marks): Explain how increasing the pressure of gases increases the rate of reaction. (3)
June 2021, Paper 1, Q9(a)(i) (1 mark): State why the mass of the contents of the flask decreases. (1)
June 2021, Paper 1, Q9(a)(ii) (1 mark): State the purpose of the cotton wool. (1)
June 2021, Paper 1, Q9(a)(iii) (2 marks): Explain why sulfuric acid is not a suitable acid to use in this investigation. (2)
June 2021, Paper 1, Q9(b)(i) (4 marks): In the investigation the marble chips are in excess. Explain the shape of the graph. (4)
June 2021, Paper 1, Q9(b)(ii) (2 marks): The student repeats the experiment using the same volume of hydrochloric acid but of half the concentration of the original acid. All other conditions are kept
June 2021, Paper 1, Q9(c) (4 marks): Explain, using particle collision theory, how increasing the temperature affects the rate of a reaction. (4)
January 2021, Paper 1, Q3(b) (2 marks): Explain why solid lead iodide takes less time to form when the reaction is repeated using water at a higher temperature. (2)
January 2021, Paper 1, Q11(a)(ii) (3 marks): Describe a method to show that solid manganese(IV) oxide is a catalyst in this reaction and not a reactant. (3)
January 2021, Paper 1, Q11(b)(i) (2 marks): Calculate the mean (average) rate of reaction, in cm3 / s, in the first 120 s. (2) mean rate = cm3 / s
January 2021, Paper 1, Q11(b)(ii) (3 marks): The equation for the reaction between zinc and hydrochloric acid is Zn(s) + 2HCl(aq) → ZnCl2(aq) + H2(g) Use this equation and the particle collision theory to
January 2021, Paper 1, Q11(b)(iii) (2 marks): The student repeats the experiment at a higher temperature but keeps all other conditions the same. On the grid, draw the curve you would expect to see in this
January 2021, Paper 1, Q11(b)(iv) (2 marks): Explain why the rate of reaction is greater if the same mass of zinc powder is used instead of zinc lumps. All other conditions are kept the same. (2)
January 2021, Paper 2, Q3(a)(i) (2 marks): All the carboxylic acids are of the same concentration. Give two other variables the student should control in his investigation. (2) 1 2
January 2021, Paper 2, Q3(a)(ii) (1 mark): Give a reason why it is important to connect the gas syringe quickly. (1)
January 2021, Paper 2, Q3(b)(i) (2 marks): Calculate the mean (average) time for propanoic acid to produce 10 cm3 of hydrogen gas. (2) mean time = s
January 2021 (R), Paper 1, Q6(c) (3 marks): Explain how increasing the concentration of the hydrochloric acid affects the rate of reaction. (3)
January 2021 (R), Paper 1, Q6(d) (3 marks): The rate of reaction could also be affected by changing the temperature of the hydrochloric acid, or by using a catalyst. Explain one other way in which the rat
January 2021 (R), Paper 2, Q5(a) (1 mark): A catalyst increases the rate of this reaction. State one other property of a catalyst. (1)
January 2021 (R), Paper 2, Q5(b) (6 marks): A student has samples of three solids, X, Y and Z. The student uses this apparatus to find out which solids act as catalysts in the decomposition of hydrogen pe
January 2021 (R), Paper 2, Q5(c) (2 marks): The decomposition of hydrogen peroxide solution is exothermic. On the diagram, draw and label the reaction profiles for the reaction  without a catalyst  with
November 2020, Paper 1, Q7(a) (1 mark): State the name of the precipitate that forms. (1)
November 2020, Paper 1, Q7(b) (2 marks): The reaction is often used to investigate rates of reaction. The diagram shows the apparatus a student uses to investigate the effect of temperature on the rate
November 2020, Paper 1, Q7(c) (1 mark): The table shows the student’s results. Temperature Time until cross in °C cannot be seen in s 20 400 30 188 40 84 50 44 60 24 The highest temperature the studen
November 2020, Paper 1, Q7(d) (2 marks): The student wants to compare the rates of the reaction at the different temperatures. He uses this formula to obtain a value for each rate of reaction 1 rate =
November 2020, Paper 1, Q7(e)(i) (2 marks): Use the graph to determine a value for the rate of the reaction at 45 °C. Show on the graph how you obtained your answer. (2) rate of reaction = s−1
November 2020, Paper 1, Q7(e)(ii) (2 marks): Calculate the time that it would take for the cross not to be seen at 45 °C. (2) time = s
November 2020, Paper 1, Q7(e)(iii) (1 mark): Describe the relationship between rate of reaction and temperature shown by the graph. (1)
November 2020, Paper 1, Q7(f) (3 marks): Explain, in terms of particle collision theory, the effect that increasing the temperature has on the rate of a reaction. (3)
November 2020 (R), Paper 1, Q4(c) (1 mark): State the reason for adding a catalyst. (1)
November 2020 (R), Paper 1, Q4(d)(i) (1 mark): Plot the student’s results on the grid. (1)
November 2020 (R), Paper 1, Q4(d)(ii) (1 mark): Draw a circle on the grid around the anomalous result. (1)
November 2020 (R), Paper 1, Q4(d)(iii) (1 mark): Draw a curve of best fit through the points, ignoring the anomalous result. (1) 100 80 60 Volume of oxygen in cm3 40 20 0 0 4 8 12 16 Time in minutes
November 2020 (R), Paper 1, Q4(d)(iv) (1 mark): Suggest a mistake that the student might have made to cause the anomalous result. (1)
November 2020 (R), Paper 1, Q4(d)(v) (2 marks): Determine the volume of oxygen collected during the first 3 minutes. Show on your graph how you obtain your answer. (2) volume of oxygen = cm3
November 2020 (R), Paper 1, Q4(e)(i) (2 marks): Draw on the grid the curve you would expect the student to obtain. (2)
November 2020 (R), Paper 1, Q4(e)(ii) (3 marks): Explain how using hydrogen peroxide solution of half the concentration affects the rate of the reaction. Refer to particle collision theory in your answer. (3)
January 2020, Paper 1, Q10(a)(iii) (1 mark): State the purpose of the platinum catalyst. (1)
January 2020, Paper 2, Q5(b) (2 marks): Explain how a catalyst increases the rate of a reaction. (2)
January 2020 (R), Paper 2, Q6(b)(i) (2 marks): Explain why increasing the pressure increases the rate of this reaction. (2)
January 2020 (R), Paper 2, Q6(b)(ii) (2 marks): The rate of this reaction can also be increased by using a catalyst. Explain how using a catalyst increases the rate of a reaction. (2)
January 2020 (R), Paper 2, Q6(b)(iii) (1 mark): Give one other way that the rate of reaction between ethene gas and hydrogen gas can be increased. (1)
June 2019, Paper 1, Q5(c)(ii) (1 mark): State why a catalyst is used in this reaction. (1)
June 2019, Paper 1, Q13(a)(i) (1 mark): Plot the student’s results on the grid. (1)
June 2019, Paper 1, Q13(a)(ii) (1 mark): Draw a curve of best fit. (1) 100 80 60 Volume of hydrogen in cm3 40 20 0 0 20 40 60 80 Time in s
June 2019, Paper 1, Q13(b)(i) (2 marks): The student repeats the experiment using ● 0.043 g of magnesium ribbon ● 50 cm3 of 2.00 mol/dm3 hydrochloric acid Draw, on the grid in part (a), the curve you w
June 2019, Paper 1, Q13(b)(ii) (2 marks): The student repeats the experiment again, using ● 0.086 g of magnesium ribbon ● 50 cm3 of 2.00 mol/dm3 hydrochloric acid ● a slightly higher temperature than th
June 2019, Paper 1, Q13(c) (1 mark): The expected volume of gas produced in the first experiment is 86 cm3. Suggest why the volume collected is less than the expected volume. (1)
June 2019, Paper 1, Q13(d) (2 marks): The student uses a graduated beaker to measure the volume of dilute hydrochloric acid. Explain why it is not necessary to use a measuring cylinder in this exper
June 2019, Paper 1, Q13(e) (3 marks): The ionic equation for the reaction between magnesium and hydrochloric acid is Mg(s) + 2H+(aq) → Mg2+(aq) + H2(g) Use the information in this equation, and the
June 2019 (R), Paper 1, Q5(a)(i) (2 marks): Explain how using the cotton wool increases the accuracy of this investigation. (2)
June 2019 (R), Paper 1, Q5(a)(ii) (1 mark): Why is mass lost from the flask? (1) A acid particles are moving B gas is given off C heat energy is produced D marble chips are dissolving
June 2019 (R), Paper 1, Q5(c) (2 marks): The student uses large marble chips in the investigation. This is a graph of his results. Mass loss Time The student repeats the experiment using the same total
June 2019 (R), Paper 1, Q5(d)(i) (3 marks): Explain, using the particle collision theory, how increasing the concentration of the hydrochloric acid would affect the rate of this reaction. (3)
June 2019 (R), Paper 1, Q5(d)(ii) (3 marks): Explain, using the particle collision theory, how increasing the temperature would affect the rate of this reaction. (3)
June 2019 (R), Paper 1, Q6(b)(ii) (1 mark): State the purpose of using a catalyst. (1)

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