Chemistry 5070 · O Level · Reversible reactions and equilibrium

Reversible reactions and equilibrium — practice question

Heating a sample of zinc sulfite in a sealed system produces an equilibrium mixture. $\text{ZnSO}_3(\text{s}) \rightleftharpoons \text{ZnO}(\text{s}) + \text{SO}_2(\text{g})$ The forward reaction is endothermic.
(a)[2]

The temperature in the closed system is raised while the pressure remains constant. Predict the effect on the equilibrium position for this reaction. Explain your answer.

(b)[2]

The pressure in the closed system is reduced and the temperature is held constant. Predict how the equilibrium position for this reaction changes. Explain your answer.

(c)[3]

Calculate the greatest mass of zinc oxide that can be obtained from $25.5\,\text{g}$ of zinc sulfite.

(d)[2]

Zinc oxide can react with both aqueous sodium hydroxide and dilute hydrochloric acid, whereas sulfur dioxide reacts only with aqueous sodium hydroxide. Explain why.

(e)[2]

Solid zinc sulfite reacts with dilute nitric acid to produce sulfur dioxide gas, an aqueous zinc salt and a colourless liquid. Write the symbol equation for this reaction, including state symbols.

Worked solution & mark scheme

This 11-mark question has a full step-by-step worked solution and mark scheme. One marking point: equilibrium moves to the right / product side

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