Which of the following reactions occur at the cathode during the charging of a lead storage battery?

Options

A. `Pb^(2+)+SO_2^(−4)toPbSO_4`
B. `PbSO_(4)rarrPb^(2+)+SO_(4)""^(2-)`
C. `PbSO_4(s)+2e^(-)toPb(s)+SO_4^(2-)(aq)`
D. `PbSO_(4)+2H_(2)Orarr PbO_(2)+2H^(+)+SO_(2)""^(2-)+2e^(-)`

Answer

C

Explanation

On charging the battery by passing electric current of a suitable voltage in the opposite direction, the reaction is reversed and `PbSO_4(s)` on anode and cathode is converted into `PbO_2` and `Pb` respectively.

Anode: `PbSO_4(s)+2H_2O(l)toPbO_2(s)+SO_4^(2-)(aq)+4H^(+)(aq)+2e^(-)`

Cathode: `PbSO_4(s)+2e^(-)toPb(s)+SO_4^(2-)(aq)`

Overall cell reaction:
`2PbSO_4(s)+2H_2O(l)toPb(s)+PbO_2(s)+2H_2SO_4(aq)`