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
121–130 of 164
Question 121
3 marks · Easy
Answer and see the solution →(a)[2 marks]Draw and label a reaction profile diagram for an exothermic reaction, showing the energy of reactants, products, and the activation energy.
(b)[1 mark]Explain how a catalyst would change the shape of this diagram.
Question 122
2 marks · Easy
Answer and see the solution →The energy of the reactants is 180 kJ/mol and the energy at the peak of the reaction profile (with a catalyst) is 130 kJ/mol. Calculate the activation energy for this pathway.
Question 123
2 marks · Normal
Answer and see the solution →Explain, with reference to activation energy, how a catalyst affects a reaction profile diagram.
Question 124
4 marks · Normal
Answer and see the solution →The diagram below shows a reaction profile for an exothermic reaction, both with and without a catalyst.
Reaction profile diagram for part (b). (a)[1 mark]Identify which curve on the diagram represents the reaction with a catalyst.
(b)[1 mark]On the diagram, mark with a label 'Ea (with catalyst)' the activation energy for the catalysed reaction.
(c)[1 mark]State what happens to the enthalpy change (ΔH) of the reaction when a catalyst is added.
(d)[1 mark]Explain why the reaction happens faster when a catalyst is used.
Question 125
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 126
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 127
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 128
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 129
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 130
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.