Chemistry 0620 · IGCSE · Reversible reactions and equilibrium

Reversible reactions and equilibrium — practice question

Lime (calcium oxide) is produced by heating limestone (calcium carbonate). $\text{CaCO}_3(s) \rightleftharpoons \text{CaO}(s) + \text{CO}_2(g)$
(a(i))[1]

Is this reaction exothermic or endothermic? Explain your answer.

(a(ii))[1]

The reaction is reversible. Which feature of the equation indicates that this reaction is reversible?

(b(i))[2]

On the diagram, place the letter C to mark where the waste gases leave the furnace, and the letter L to show where the lime is taken out of the furnace.

(b(ii))[1]

Suggest why coke (carbon) is added to the furnace.

(c)[2]

Explain why farmers apply lime to acidic soils.

(d(i))[2]

Describe the test for sulfate ions. Give the test and the result.

(d(ii))[1]

Deduce the formula of this silicate.

(e(i))[1]

What is the most likely pH of a strongly alkaline solution? Draw a ring around the correct answer: pH 2, pH 6, pH 7, pH 12.

(e(ii))[1]

Complete the equation for this reaction. $\text{Ca(OH)}_2 + \text{CO}_2 \rightarrow \text{CaCO}_3 + \ldots$

(e(iii))[3]

Use the information in (e)(i) and (e)(ii) to help explain these observations.

Worked solution & mark scheme

This 15-mark question has a full step-by-step worked solution and mark scheme. One marking point: endothermic since heating is needed

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