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
51–60 of 69 · Normal
Question 51
3 marks · Normal
Answer and see the solution →A reaction without a catalyst has an activation energy of 180 kJ/mol. When a catalyst is added, the activation energy decreases to 100 kJ/mol.
Calculate the difference in activation energy as a result of adding the catalyst.
Explain what this change means for the number of successful collisions.
Question 52
3 marks · Normal
Answer and see the solution →A student claims, "A catalyst lowers the energy of the reactants."
Discuss whether this statement is correct, using ideas from reaction profile diagrams and activation energy.
Question 53
2 marks · Normal
Answer and see the solution →State what a reaction profile diagram shows about the effect of a catalyst on: (i) the activation energy (ii) the overall energy change (enthalpy change, ).
Question 54
4 marks · Normal
Answer and see the solution →(a)[2 marks]The diagram below shows the reaction profile for a chemical reaction without a catalyst.
Reaction profile diagram for a reaction without a catalyst. Draw on the diagram, using a dashed curve, how the reaction profile would look if a catalyst was used.
(b)[2 marks]Explain, using the diagram, how the catalyst affects the reaction.
Question 55
3 marks · Normal
Answer and see the solution →A reaction has reactants at an energy level of 95 kJ/mol, a peak (without a catalyst) at 155 kJ/mol, and products at 65 kJ/mol.
A catalyst provides an alternative pathway with a peak at 110 kJ/mol.
Calculate:
(a)[1 mark]The activation energy without a catalyst.
(b)[1 mark]The activation energy with a catalyst.
(c)[1 mark]The difference in activation energy caused by the catalyst.
Question 56
3 marks · Normal
Answer and see the solution →A student says: 'When you add a catalyst, more particles in the reaction mixture have the required activation energy to react.'
Explain, with reference to reaction profile diagrams, whether this statement is correct.
Question 57
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 58
2 marks · Normal
Answer and see the solution →State two reasons why catalysts are important in industrial chemical reactions.
Question 59
4 marks · Normal
Answer and see the solution →Read the passage below and answer the questions that follow.
(a)[2 marks]Explain how a catalyst lowers the activation energy of a reaction.
(b)[1 mark]State what effect a catalyst has on the overall enthalpy change (ΔH) of the reaction.
(c)[1 mark]Does the catalyst get used up in the reaction? Explain your answer.
Question 60
3 marks · Normal
Answer and see the solution →The diagram below shows the energy changes in a reaction with and without a catalyst.
Reaction profile showing catalysed and uncatalysed paths. The activation energy for the uncatalysed reaction is 100 kJ/mol, and the activation energy for the catalysed reaction is 60 kJ/mol. The enthalpy change (ΔH) for the reaction is -40 kJ/mol.
Calculate the difference in activation energy between the catalysed and uncatalysed routes, and explain what effect this has on the rate of reaction.