Chemistry 5070 · O Level · Preparation of salts

Preparation of salts — practice question

Copper can react with concentrated nitric acid. $\text{Cu}(s) + 4\text{HNO}_3(aq) \rightarrow \text{Cu(NO}_3)_2(aq) + 2\text{NO}_2(g) + 2\text{H}_2\text{O}(l)$
(a)[1]

Suggest what you would see when copper reacts with concentrated nitric acid.

(b(i))[1]

Suggest the name of the salt with formula Cu(NO$_3$)$_2$.

(b(ii))[1]

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

(c)[3]

An excess of copper is added to 25.0 cm$^3$ of 16.0 mol/dm$^3$ HNO$_3$. Calculate the volume of NO$_2$ produced at room temperature and pressure.

(d)[1]

When heated, Cu(NO$_3$)$_2$ breaks down to give CuO, NO$_2$ and O$_2$. Construct the equation for this reaction.

(e(i))[2]

A student adds aqueous ammonia drop by drop to a sample of $\text{Cu(NO}_3)_2\text{(aq)}$ until the reagent is in excess. Describe what is seen.

(e(ii))[1]

The student repeats the experiment, but this time uses aqueous sodium hydroxide instead of aqueous ammonia. Describe what is observed.

Worked solution & mark scheme

This 10-mark question has a full step-by-step worked solution and mark scheme. One marking point: Blue solution / brown gas / bubbles of gas / copper metal disappears

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