Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Chapter
Rates of Reaction
164 practice questions
Topics covered
- Experiments to measure the rate of reaction19 practice questions
- Explaining what's happening19 practice questions
- Changing the surface area of the reactants19 practice questions
- Changing the concentration of the reactants19 practice questions
- Changing the pressure on the reaction19 practice questions
- What are catalysts?19 practice questions
- How does a catalyst work?20 practice questions
- Catalysts in industry19 practice questions
Practice questions
151–160 of 164
Question 151
5 marks · Hard
Answer and see the solution →The diagram below shows the energy changes during a chemical reaction.
(a)[2 marks]Explain, in terms of activation energy, how a catalyst increases the rate of a reaction.
(b)[2 marks]A student suggests that adding a catalyst would change the total enthalpy change (ΔH) of a reaction. Is this correct? Explain your answer.
(c)[1 mark]Describe, using a reaction profile diagram, what happens to the activation energy and enthalpy change of a reaction when a catalyst is used.
Question 152
2 marks · Hard
Answer and see the solution →Describe two key features that should be shown on a reaction profile diagram to illustrate the effect of a catalyst on a reaction.
Question 153
2 marks · Hard
Answer and see the solution →Ammonia is produced in the Haber process, which requires high temperatures and pressures. The process uses an iron catalyst.
Explain two ways that using a catalyst in the Haber process is important for the chemical industry.
Question 154
5 marks · Easy
Answer and see the solution →Some students investigate how quickly a metal carbonate reacts with dilute acid. They want to investigate the effect of changing the surface area of the solid on the rate of reaction.
(a)[2 marks]Describe how the students could carry out an experiment to investigate the effect of surface area on the rate of reaction between calcium carbonate and dilute hydrochloric acid.
(b)[1 mark]State one way the results from this experiment could be measured.
(c)[2 marks]Explain, using collision theory, why smaller pieces of calcium carbonate react faster than large pieces when added to hydrochloric acid.
Question 155
5 marks · Easy
Answer and see the solution →The diagram below shows apparatus used to measure the rate of a reaction between marble chips (calcium carbonate) and dilute hydrochloric acid.
Apparatus for measuring mass loss. (a)[1 mark]State what happens to the mass reading as the reaction occurs.
(b)[1 mark]Suggest why a cotton wool plug is placed in the neck of the flask.
(c)[2 marks]Describe two different ways to increase the rate of this reaction.
(d)[1 mark]Explain, using collision theory, why increasing the temperature increases the rate of reaction.
Question 156
5 marks · Easy
Answer and see the solution →A student carries out an experiment to measure how quickly hydrogen peroxide decomposes using a catalyst. The volume of oxygen gas collected every 30 seconds is shown on a graph: the curve is steep at first, then becomes less steep and finally flat.
(a)[1 mark]State one piece of apparatus the student could use to collect the oxygen gas.
(b)[1 mark]Describe how using a different catalyst could help the student measure the effect of catalysts on the rate.
(c)[1 mark]State what happens to the rate of reaction as shown by the graph.
(d)[2 marks]Explain why the rate of reaction changes in this way, using ideas from collision theory.
Question 157
5 marks · Easy
Answer and see the solution →A student investigates the rate of reaction between excess marble chips (calcium carbonate) and dilute hydrochloric acid in a flask. The CO produced escapes, causing the total mass to decrease. The student records the following results:
Data for the reaction Time (min) Mass lost (g) 0 0.00 1 0.52 2 0.81 3 0.95 (a)[2 marks]Calculate the average rate of reaction in g/min during the first 2 minutes. Show your working.
(b)[3 marks]Use collision theory to explain why the rate of reaction changes after the first 2 minutes. Refer to the results from part (a) in your answer.
Question 158
6 marks · Normal
Answer and see the solution →A student investigates the reaction between zinc granules and dilute hydrochloric acid. She wants to find out how both the surface area of zinc and the concentration of acid affect the rate of reaction.
(a)[1 mark]State what will happen to the rate of reaction if she uses powdered zinc instead of granules, keeping everything else the same.
(b)[2 marks]Explain, in terms of particles and collisions, why your answer in (a) is correct.
(c)[1 mark]Next, she repeats the experiment using the same mass of zinc powder but halves the concentration of hydrochloric acid. Predict how the rate of reaction changes, compared to the experiment with original concentration.
(d)[2 marks]Explain your answer in (c).
Question 159
6 marks · Normal
Answer and see the solution →A chemist prepares a solution by diluting hydrochloric acid with water, then reacts it with iron filings instead of an iron bar.
(a)[2 marks]Explain why the iron filings react faster with hydrochloric acid than a single iron bar, assuming the same mass is used.
(b)[3 marks]The chemist mixes 10.0 cm³ of 2.00 mol/dm³ hydrochloric acid with 15.0 cm³ of distilled water to make a total solution volume of 25.0 cm³.
Calculate the concentration of hydrochloric acid in the diluted solution. Show your working.
(c)[1 mark]State how doubling the concentration of hydrochloric acid (in a different experiment) would affect the rate of reaction with iron filings. Give a reason for your answer.
Question 160
6 marks · Normal
Answer and see the solution →A student compares two reactions:
• Reaction 1: 5.0 g of solid calcium carbonate powder is added to 25.0 cm³ of 2.00 mol/dm³ hydrochloric acid. • Reaction 2: 5.0 g of solid calcium carbonate lumps is used with 25.0 cm³ of 1.00 mol/dm³ hydrochloric acid.
For both experiments, the mass of CO₂ gas given off in the first 30 seconds is recorded.
(a)[2 marks]In Reaction 1, the student finds the mass of CO₂ lost after 30 seconds is 0.36 g. Calculate the average rate of reaction during this time. Give your answer in g/s.
(b)[2 marks]Explain why Reaction 1 is expected to be faster than Reaction 2, using both surface area and concentration in your answer.
(c)[2 marks]In Reaction 2, the student records a mass loss of 0.13 g in the first 30 seconds. Calculate the average rate of reaction for Reaction 2.