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
131–140 of 164
Question 131
4 marks · Normal
Answer and see the solution →The table shows energy values for a chemical reaction.
Description Energy (kJ/mol) Reactants 75 Peak without catalyst 142 Peak with catalyst 95 Products 45 (a)[1 mark]Calculate the activation energy for the uncatalysed reaction.
(b)[1 mark]Calculate the activation energy for the catalysed reaction.
(c)[1 mark]Calculate the overall energy change () for the reaction.
(d)[1 mark]State how the catalyst changes the reaction profile diagram.
Question 132
2 marks · Hard
Answer and see the solution →The diagram below shows a reaction profile for an exothermic reaction. The activation energy for the uncatalysed reaction is much larger than for the catalysed reaction.
Reaction profile for an exothermic reaction (uncatalysed and catalysed). Describe what the dashed line on this diagram represents. Explain how a catalyst causes this change.
Question 133
5 marks · Hard
Answer and see the solution →A student draws the following reaction profile diagram for a certain chemical reaction:
Reaction profile for a chemical reaction. Use the diagram to answer the questions below.
(a)[1 mark]State the term used for the energy difference from the reactants up to the peak without a catalyst.
(b)[2 marks]Describe how the diagram shows the effect of a catalyst on the reaction.
(c)[2 marks]Explain why many more particles in the reaction mixture can react when a catalyst is used, referring to the activation energy.
Question 134
2 marks · Hard
Answer and see the solution →A student says that using a catalyst lowers the energy of the reactants in a chemical reaction. Evaluate this statement. Use ideas from reaction profile diagrams in your answer.
Question 135
1 mark · Easy
Answer and see the solution →State one reason why catalysts are important in industrial chemical processes.
Question 136
3 marks · Easy
Answer and see the solution →(a)[1 mark]State what is meant by activation energy.
(b)[1 mark]Explain how a catalyst affects the activation energy of a reaction.
(c)[1 mark]Explain why the energy change (enthalpy change) for a reaction does not change when a catalyst is used.
Question 137
2 marks · Easy
Answer and see the solution →Describe how you could show that a new powder is a catalyst for the decomposition of a solution. Include the key observations needed to confirm it is a catalyst.
Question 138
3 marks · Easy
Answer and see the solution →The contact process for making sulfuric acid uses vanadium(V) oxide as a catalyst. In one experiment, 100 cm³ of sulfur dioxide and excess oxygen were reacted at 450°C and 2 atm, both with and without the catalyst. With the catalyst, the reaction reached equilibrium in 2 minutes. Without the catalyst, it took 10 minutes.
(a)[1 mark]How does the catalyst affect the rate of the reaction?
(b)[1 mark]Does the catalyst increase the amount of sulfuric acid produced at equilibrium? Give a reason for your answer.
(c)[1 mark]Explain why using a catalyst is economically important in this reaction.
Question 139
1 mark · Easy
Answer and see the solution →State how a catalyst affects the activation energy of a reaction.
Question 140
3 marks · Easy
Answer and see the solution →(a)[3 marks]Draw a fully labelled reaction profile diagram for a reaction that is exothermic, showing the effect of a catalyst.