Reversible reactions and equilibrium: past paper questions
Real questions on reversible reactions and equilibrium
The newest 20 of 73 written questions. Open one to see it on the real paper.
- 0620/41 · May/June 2026 · Q6a(ii)[1]
When zinc oxide reacts with aqueous sodium hydroxide it forms sodium zincate. Sodium zincate contains sodium ions, Na + , and zincate ions, ZnO 22– . Write the formula of sodium zincate.
See it on the paper → - 0620/41 · May/June 2026 · Q6a(iii)[2]
The reaction between zinc oxide and dilute sulfuric acid forms aqueous zinc sulfate as one of the products. Write the symbol equation for the reaction between zinc oxide and dilute sulfuric acid.
See it on the paper → - 0620/41 · May/June 2026 · Q6c[3]
Dinitrogen tetroxide, N 2 O 4 , decomposes into nitrogen dioxide, NO 2 . The reaction is reversible. N 2 O 4 (g) 2NO 2 (g) The forward reaction is endothermic. A mixture of N 2 O 4 and NO 2 gases are allowed to reach equilibrium in a closed container. Complete Table 6.1 using only the words increases, decreases or no c...
See it on the paper → - 0620/42 · 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. (ii)
See it on the paper → - 0620/42 · May/June 2026 · Q4c(iii)[1]
Explain why increasing the pressure has no effect on the position of equilibrium.
See it on the paper → - 0620/42 · May/June 2026 · Q4c(iv)[2]
Explain why adding an alkali moves the position of equilibrium to the left.
See it on the paper → - 0620/43 · May/June 2026 · Q6c(ii)[3]
Complete Table 6.1 using the words increases, decreases or no change. Table 6.1 change in condition effect on the equilibrium yield of SO 3 (g) decrease the pressure increase the temperature remove the catalyst
See it on the paper → - 0620/43 · May/June 2026 · Q6c(iii)[1]
Name the industrial process in which sulfur dioxide is converted into sulfur trioxide.
See it on the paper → - 0620/42 · February/March 2026 · Q4a[2]
reversible (a) State how the information shows that this reaction is reversible and exothermic.
See it on the paper → - 0620/31 · October/November 2025 · Q3a(i)[1]
Name the positive ion that has the highest concentration. (i)
See it on the paper → - 0620/41 · October/November 2025 · Q4c[5]
The equation for the reaction is shown. SF 4 (g) + 2H 2 O(g) SO 2 (g) + 4HF(g) ΔH = –54 kJ / mol State the effect, if any, on the position of equilibrium when the following changes are made. Give a reason for each of your answers. • The pressure is increased. • The temperature is increased. A catalyst is added. •
See it on the paper → - 0620/43 · October/November 2025 · Q4a(i)[2]
Describe a reversible reaction at equilibrium in terms of: • the rate of the forward reaction and the rate of the reverse reaction • the concentrations of reactants and products.
See it on the paper → - 0620/43 · October/November 2025 · Q4a(ii)[3]
Complete Table 4.1 using only the words increases, decreases or no change. Table 4.1 change to condition effect on the rate of the forward reaction effect on the equilibrium concentration of PCl 5 the pressure is decreased a catalyst is added increases
See it on the paper → - 0620/43 · October/November 2025 · Q4a(iii)[1]
When the temperature of the equilibrium mixture is increased, the equilibrium concentration of PCl 5 decreases. State what conclusion about the forward reaction can be made from this information.
See it on the paper → - 0620/31 · 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 → - 0620/32 · 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 → - 0620/41 · 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 → - 0620/41 · 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 → - 0620/41 · May/June 2025 · Q5b(i)[2]
State two disadvantages of using a pressure below 75 atmospheres.
See it on the paper → - 0620/41 · 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 →
What examiners said
Comprehensive responses • Most candidates knew that the bidirectional arrow showed the reaction was reversible and a negative ΔH value showed the reaction was exothermic. Limited responses • Some candidates referred to the reversible symbol without saying what that symbol was.
— Examiner report, February/March 2026, 0620/42 Q4(a) (Cambridge)
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, 0620/31 Q7(a)(iii) (Cambridge)
The majority of candidates answered this question correctly.
— Examiner report, May/June 2025, 0620/32 Q7(b) (Cambridge)
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