Chemistry 0620 · IGCSE · Preparation of salts

Preparation of salts — practice question

Copper(II) sulfate is given by the formula $\text{CuSO}_4$. In water, copper(II) sulfate forms a blue solution. A sample of aqueous copper(II) sulfate is prepared by adding excess copper(II) oxide, CuO, to hot dilute sulfuric acid, $\text{H}_2\text{SO}_4$.
(a)[2]

Complete the symbol equation for this reaction. Add state symbols. $\text{CuO}$(......) + $\text{H}_2\text{SO}_4$(......) $\rightarrow$ $\text{CuSO}_4$(......) + .................(l)

(b)[1]

State one observation that shows copper(II) oxide has been added in excess.

(c)[1]

Describe how aqueous copper(II) sulfate may be separated from the reaction mixture.

(d(i))[1]

State what is meant by hydrated.

(d(ii))[1]

Write the formula for hydrated copper(II) sulfate.

(d(iii))[2]

Describe how crystallisation is carried out.

(e(i))[1]

State why aqueous copper(II) sulfate is able to conduct electricity.

(e(ii))[2]

Give two reasons why the electrodes are made of graphite.

(e(iii))[1]

Describe how the appearance of the electrolyte changes during electrolysis of aqueous copper(II) sulfate.

(e(iv))[1]

Describe what is seen at the cathode during electrolysis of aqueous copper(II) sulfate.

(e(v))[3]

Write the ionic half-equation for the reaction at the anode.

(e(vi))[2]

State two differences seen if the electrolysis is repeated using copper electrodes instead of graphite electrodes.

Worked solution & mark scheme

This 18-mark question has a full step-by-step worked solution and mark scheme. One marking point: $\text{H}_2\text{O}$

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