Ncert Exercises & Solutions

The correct statement about charging of the lead storage battery is:

1. PbSO₄ anode is reduced to Pb.

2. PbSO₄ cathode is reduced to Pb.

3. PbSO₄ cathode is oxidised to Pb.

4. PbSO₄ anode is oxidised to PbO₂.

HINT: $2 {PbSO}_{4} (s) + 2 H_{2} O \to Pb (s) + {PbO}_{2}$ $(s) + 4 H^{+} (aq .) + 2 {SO}_{4}^{2 -} (aq .)$ [ Charging reaction]

Explanation:

While charging the lead storage battery the reaction occurring on the cell is reversed and PbSO₄ (s) on the anode and cathode

is converted into Pb and PbO₂ respectively.

The electrode reactions are as follows:

At anode ${PbSO}_{4} (s) + 2 e^{-} \to Pb (s) + {SO}_{4}^{2 -} (aq)$ (Reduction)

At cathode ${PbSO}_{4}$ $(s) + 2 H_{2} O \to {PbO}_{2}$ $(s) + {SO}_{4}^{2 -} + 4 H^{+} + 2 e^{-}$ (Oxidation)

Overall reaction

2 {PbSO}_{4} (s) + 2 H_{2} O \to Pb (s) + {PbO}_{2}

(s) + 4 H^{+} (aq .) + 2 {SO}_{4}^{2 -} (aq .)

Hence, option first is the correct option.