Question

While charging the lead storage battery ______________.
(i) PbSO4 anode is reduced to Pb.
(ii) PbSO4 cathode is reduced to Pb
(iii) PbSO4 cathode is oxidised to Pb.
(iv) PbSO4 anode is oxidised to PbO2.


NCERT Class XII
Chemistry - Exemplar Problems

Chapter 3. Electrochemistry

Answer 1

answer : option (a) PbSO4 anode is reduced to Pb.

explanation : while charging the lead storage battery, the reaction occurs on the battery is reversed.

i mean, while charging, PbSO4 is converted into Pb on anode and on cathode, PbSO4 is converted into PbO2.

for understanding batter,

reaction occurs on anode,

$PbSO_4+2e^-\rightarrow Pb+SO_4^{2-}$, here you see PbSO4 is reduced into Pb.

and reaction occurs on cathode,

$PbSO_4+2H_2O\rightarrow PbO_2+SO_4^{2-}+4H^++2e^-$, here PbSO4 is oxidised into PbO2.

and overall reaction is ...

$2PbSO_4+2H_2O\rightarrow Pb+PbO_2+4H^++2SO_4^{2-}$