Chemistry 5070 · O Level · Redox

Redox — practice question

Copper is made to react with hot concentrated aqueous sulfuric acid. $\text{Cu}(s) + 2\text{H}_2\text{SO}_4(aq) \rightarrow \text{CuSO}_4(aq) + \text{SO}_2(g) + 2\text{H}_2\text{O}(l)$
(a)[1]

Suggest what you would see when copper reacts with hot concentrated aqueous sulfuric acid.

(b(i))[1]

Name the salt with formula $\text{CuSO}_4$.

(b(ii))[1]

Copper is oxidised when it reacts with concentrated sulfuric acid. Use the equation to explain how copper has been oxidised.

(c)[3]

An excess of copper is added to $25.0\,\text{cm}^3$ of hot $14.0\,\text{mol dm}^{-3}\,\text{H}_2\text{SO}_4$. Use this information, together with the equation, to calculate the greatest possible volume of $\text{SO}_2$ made. The gas volume is measured at room temperature and pressure.

(d(i))[1]

Describe what would be observed when aqueous sodium hydroxide is added one drop at a time until it is in excess.

(d(ii))[2]

The student repeats the test, but aqueous ammonia is used instead of aqueous sodium hydroxide. Describe what would be observed.

(e)[1]

Copper(I) chloride, $\text{CuCl}$, decomposes to give $\text{CuCl}_2$ and $\text{Cu}$. Write the equation for this reaction.

Worked solution & mark scheme

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