Chemistry 0620 · IGCSE · Electrolysis

Electrolysis — practice question

This question concerns electrolysis. Concentrated hydrochloric acid is electrolysed with the apparatus shown. The diagram labels: wire, carbon electrodes, concentrated hydrochloric acid.
(a(i))[2]

Complete the ionic half-equation that represents this reaction. ________Cl$^-$(aq) $\rightarrow$ ________(g) + ________e$^-$

(a(ii))[1]

State whether oxidation or reduction occurs, and explain your answer.

(b)[1]

Describe what is observed at the cathode.

(c)[2]

Write the ionic half-equation for the cathode reaction.

(d(i))[1]

Suggest the pH of the electrolyte at the start of the experiment.

(d(ii))[2]

State how the pH changes, if at all, during the experiment. Explain your answer.

(e)[2]

Describe what is seen at the cathode and at the anode.

(f)[2]

State two properties of graphite (carbon) that make it suitable for electrode use.

Worked solution & mark scheme

This 13-mark question has a full step-by-step worked solution and mark scheme. One marking point: 2Cl- → Cl2 + 2e-

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