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During the recharging of a lead storage battery, which reaction takes place at the cathode?

1. Pb2+ + 2e− → Pb
2. Pb2+ + SO4²− → PbSO4
3. Pb → Pb2+ + 2e−
4. PbSO4 + 2H2O → 2PbO2 + 4H+ + SO4²− + 2e−

Correct answer: Pb2+ + 2e− → Pb

Solution

During recharging (electrolysis), reduction occurs at the cathode: PbSO4 + 2e- -> Pb + SO4^2-, i.e. Pb2+ + 2e- -> Pb. The answer is the reduction of Pb2+ to Pb.

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