Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Section
How does a catalyst work?
20 practice questions
Practice questions
1–3 of 3 · Hard
Question 1
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 2
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 3
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.