Chemistry 5070 · O Level · Reversible reactions and equilibrium

Reversible reactions and equilibrium — practice question

If a sample of zinc carbonate is heated in a closed system, an equilibrium mixture results. $\text{ZnCO}_3(\text{s}) \rightleftharpoons \text{ZnO}(\text{s}) + \text{CO}_2(\text{g})$ The forward reaction takes in heat.
(a)[2]

The temperature of the closed system is reduced while the pressure stays unchanged. Predict the effect on the position of equilibrium for this reaction. Explain your answer.

(b)[2]

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

(c)[3]

Calculate the greatest mass of zinc oxide that can be produced from $4.23\,\text{g}$ of zinc carbonate.

(d)[2]

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

(e)[2]

A solid sample of zinc carbonate reacts with dilute nitric acid to form a colourless solution and a gas is released as bubbles. 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 shifts to the left / toward the reactants / zinc carbonate side

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