Homogeneous and heterogeneous catalysts: past paper questions
Real questions on homogeneous and heterogeneous catalysts
The newest 20 of 60 written questions. Open one to see it on the real paper.
- 9701/21 · October/November 2025 · Q4a(ii)[2]
Suggest a suitable reagent for reaction 2.
See it on the paper → - 9701/21 · October/November 2025 · Q4a(iv)[1]
C 2 H 5 CH 2 OH can be directly converted to C 3 H 6 . Suggest the reagent and conditions for this conversion.
See it on the paper → - 9701/23 · October/November 2025 · Q3c(i)[1]
The reaction is initiated by the bond fission of Cl 2 . State the type of bond fission shown in the initiation step.
See it on the paper → - 9701/23 · October/November 2025 · Q3c(ii)[2]
Complete the equations to show the two propagation steps that follow the initiation step. propagation 1 C 5 H 10 + C 5 H 9 • +
See it on the paper → - 9701/23 · October/November 2025 · Q3c(iii)[1]
The final step is shown. C 5 H 9 • + Cl • C 5 H 9 Cl Give the name for this step in the reaction.
See it on the paper → - 9701/41 · October/November 2025 · Q3a[1]
Solid manganese( IV ) oxide, MnO 2 , catalyses the decomposition of hydrogen peroxide. 2H 2 O 2 (aq) 2H 2 O(l) + O 2 (g) State the type of catalysis for this reaction. Explain your answer.
See it on the paper → - 9701/42 · October/November 2025 · Q2e[2]
NO 2 is present in the exhaust gases of cars. It can react with carbon monoxide, CO, on the surface of a heterogeneous catalyst in the car’s catalytic converter. Describe the mode of action of this heterogeneous catalyst.
See it on the paper → - 9701/21 · May/June 2025 · Q3a(iii)[1]
State the role of nickel when it is added to reaction 1. (iii)
See it on the paper → - 9701/21 · May/June 2025 · Q3a(iv)[1]
Annotate Fig. 3.2 to show the effect of adding nickel to reaction 1 at temperature T. number of molecules E A energy
See it on the paper → - 9701/43 · May/June 2025 · Q2c[3]
Sulfur dioxide, SO 2 , reacts very slowly with oxygen in the atmosphere, forming sulfur trioxide, SO 3 . This reaction is much faster in the presence of NO. Explain the role of NO in this process. Include chemical equations in your answer.
See it on the paper → - 9701/42 · February/March 2025 · Q6b(i)[1]
Suggest the type of reaction that occurs in step 1.
See it on the paper → - 9701/41 · October/November 2024 · Q3b(i)[1]
Identify two metals that act as heterogeneous catalysts in the removal of NO 2 from the exhaust gases of car engines. and
See it on the paper → - 9701/42 · October/November 2024 · Q1b(ii)[1]
Name the metal catalyst in the Haber process and explain why it is a heterogeneous catalyst. metal
See it on the paper → - 9701/42 · October/November 2024 · Q1b(iii)[2]
Platinum acts as a heterogeneous catalyst in the removal of nitrogen dioxide, NO 2 , from the exhaust gases of car engines. Describe the mode of action of a platinum catalyst in this process.
See it on the paper → - 9701/42 · October/November 2024 · Q1b(iv)[1]
NO 2 acts as a homogeneous catalyst in the oxidation of atmospheric sulfur dioxide, SO 2 . Write equations for the two reactions that occur. equation
See it on the paper → - 9701/43 · October/November 2024 · Q3b(i)[1]
Identify two metals that act as heterogeneous catalysts in the removal of NO 2 from the exhaust gases of car engines. and
See it on the paper → - 9701/43 · October/November 2024 · Q3b(ii)[2]
Iron acts as a heterogeneous catalyst in the Haber process. Describe the mode of action of this iron catalyst.
See it on the paper → - 9701/43 · October/November 2024 · Q3b(iv)[1]
Explain the difference between a homogeneous catalyst and a heterogeneous catalyst.
See it on the paper → - 9701/42 · February/March 2024 · Q6b(i)[1]
State the essential conditions for reaction 1.
See it on the paper → - 9701/43 · October/November 2023 · Q3d[1]
The decomposition of H 2 O 2 (aq) is catalysed by aqueous iron(III) chloride and by silver metal. Identify which of these two catalysts is acting as a homogeneous catalyst. Explain your answer. homogeneous catalyst explanation
See it on the paper →
What examiners said
Most candidates correctly identified the catalyst as FeCl3 stating it was in the same phase as H2O2.
— Examiner report, October/November 2023, 9701/43 Q3(d) (Cambridge)
It was generally well known how a catalyst affects a reaction. Some ambiguity was seen in answers that described the effect of catalysts as increasing the number of collisions between particles rather than increasing the frequency of successful collisions.
— Examiner report, May/June 2023, 9701/22 Q4(c)(iv) (Cambridge)
Stronger candidates clearly described the regeneration of the catalyst. Some candidates were vague and imprecise, for example ‘the catalyst did not change in the reaction’.
— Examiner report, May/June 2023, 9701/22 Q4(c)(v) (Cambridge)
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