The electrolysis of sodium chloride solution

2 marks · Easy

Write a balanced half-equation for the cathode reaction during the electrolysis of sodium chloride solution when hydrogen gas is formed.

Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.

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2H^+ (aq) + 2e^- \rightarrow H_2 (g)

Must show: 2H^+ (aq), 2e^-, H_2 (g)

Also accept: 2H_2O(l) + 2e^- \rightarrow H_2(g) + 2OH^-(aq)

Common mistakes: Unbalanced equation; Wrong number of electrons

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Marking points

M1 · 1 mark · Sets up a correct half-equation for hydrogen produced at cathode.

A1 · 1 mark · Balances the half-equation with correct species and charges.

Worked solution

Or: 2H_2O(l) + 2e^- → H_2(g) + 2OH^-(aq)