Reversible reactions and equilibrium: past paper questions
Real questions on reversible reactions and equilibrium
The newest 20 of 53 written questions. Open one to see it on the real paper.
- 0971/42 · May/June 2026 · Q4c(ii)[2]
Describe this equilibrium in terms of: ¢ the rate of the forward reaction and the rate of the reverse reaction * the concentration of the reactants and of the products.
See it on the paper → - 0971/42 · May/June 2026 · Q4c(iii)[1]
Explain why increasing the pressure has no effect on the position of equilibrium.
See it on the paper → - 0971/42 · May/June 2026 · Q4c(iv)[2]
Explain why adding an alkali moves the position of equilibrium to the left.
See it on the paper → - 0971/31 · May/June 2025 · Q7a(iii)[1]
Fig. 7.1 shows the incomplete reaction pathway diagram for the reaction in Experiment 4. progress of reaction Fig. 7.1 Complete Fig. 7.1 by labelling: • • the vertical axis the reactants
See it on the paper → - 0971/32 · May/June 2025 · Q7b[1]
The reaction of hydrogen with nitrogen is a reversible reaction. Write the symbol that shows a reversible reaction.
See it on the paper → - 0971/41 · May/June 2025 · Q4b(i)[3]
State three typical conditions for the reaction between nitrogen and hydrogen in the Haber process.
See it on the paper → - 0971/41 · May/June 2025 · Q5a[2]
State what happens to the concentration of CH 3 OH when the reaction is at equilibrium. Explain your answer in terms of rate of forward and reverse reactions.
See it on the paper → - 0971/41 · May/June 2025 · Q5b(i)[2]
State two disadvantages of using a pressure below 75 atmospheres.
See it on the paper → - 0971/41 · May/June 2025 · Q5b(ii)[2]
Complete Table 5.1 using only the words increases, decreases or no change. Table 5.1 effect on the concentration of CH 3 OH(g) at equilibrium effect on the rate of the reverse reaction catalyst is added
See it on the paper → - 0971/41 · May/June 2025 · Q5b(iii)[1]
If a temperature of more than 250 °C is used, the yield of methanol decreases. State what can be deduced about the forward reaction.
See it on the paper → - 0971/42 · May/June 2025 · Q6d(i)[4]
Complete Table 6.1 to show the effect, if any, on the concentration of C 2 H 4 (g) when the following changes to the conditions are applied. Only use the words increases, decreases or no change. Table 6.1 effect on the concentration of C 2 H 4 (g) at equilibrium change to condition temperature is decreased some C 2 H 5...
See it on the paper → - 0971/42 · October/November 2024 · Q1i[1]
is a reactant in the Haber process.
See it on the paper → - 0971/42 · October/November 2024 · Q3d[2]
Chloride P is converted to chloride Q by reaction with chlorine in a closed system. The reversible reaction reaches an equilibrium. S 2 Cl 2 (g) + Cl 2 (g) P 2SCl 2 (g) Q The forward reaction is exothermic. Suggest two changes to the conditions which will result in a decrease in the concentration of chloride Q at equil...
See it on the paper → - 0971/41 · May/June 2024 · Q4a[2]
State what is meant by the term equilibrium.
See it on the paper → - 0971/41 · May/June 2024 · Q4b(i)[1]
Explain why the position of equilibrium does not change.
See it on the paper → - 0971/41 · May/June 2024 · Q4b(ii)[1]
Suggest why the colour of the mixture of gases turns darker purple.
See it on the paper → - 0971/41 · May/June 2024 · Q4c[1]
The temperature of the mixture of gases is decreased. All other conditions stay the same. The mixture of gases turns lighter purple. State what can be deduced about the forward reaction from this information.
See it on the paper → - 0971/41 · May/June 2024 · Q4e(ii)[1]
State the effect on the position of equilibrium when a catalyst is used.
See it on the paper → - 0971/42 · May/June 2024 · Q4e[4]
Complete Table 4.1 to show the effect, if any, for each change of condition. Table 4.1 effect on the concentration of carboxylic acid X at equilibrium change of condition temperature is decreased concentration of CH 3 CH 2 COOCH 3 is decreased more alcohol Y is added a catalyst is added
See it on the paper → - 0971/42 · May/June 2024 · Q4f(i)[2]
Suggest how the pH of the reaction mixture changes from the start of the reaction until equilibrium is reached. Assume alcohols and esters are neutral. pH at start of reaction pH at equilibrium
See it on the paper →
What examiners said
It was anticipated that candidates would be able to use the symbols for the reactants and products from Experiment 4 and to label the vertical axis as ‘energy’.
— Examiner report, May/June 2025, 0971/31 Q7(a)(iii) (Cambridge)
This was answered very well. The most common errors were incorrectly stated units and omission of the word ‘catalyst’ when referring to iron. The catalyst was occasionally named as vanadium(V) oxide.
— Examiner report, May/June 2025, 0971/41 Q4(b)(i) (Cambridge)
This was answered quite well. ‘Concentrations of reactants and products are equal’ and ‘rates of reactions are constant’ were seen occasionally. ‘Forward reaction is equal to reverse reaction’ was another statement that gained no credit.
— Examiner report, May/June 2025, 0971/41 Q5(a) (Cambridge)
Past papers, syllabus and examiner reports © UCLES (Cambridge University Press & Assessment). Questions are matched to topics from the official syllabus. AssessPro is independent and not endorsed by Cambridge.