Question

8. While charging the lead storage battery _________ . [NCERT Exemplar] (a) PbSO4 anode is reduced to Pb. (b) PbSO4 cathode is reduced to Pb. (c) PbSO4 cathode is oxidised to Pb. (d) PbSO4 anode is oxidised to PbO2.

Answer 1

Answer:

(a) PbSO4 anode is reduced to Pb.

Explanation:

Cells which can be recharged are known as secondary cells. They can be recharged by passing a direct current through them. An example of a secondary cell is the lead storage battery used in motor cars.

During the process of recharging, the electrodes in the cell are reversed from what we have  know to occur during discharging because it is electrolized.

At the anode: The lead (II) tetraoxosulphate (VI)  absorbs two electrons to become reduced to Pb. Thus at the anode PbSO₄ is reduced to Pb.

$PbSO_4+2e^-\rightarrow Pb+SO_4^{2-}$

At the cathode:

The electrons from the anode are accepted at the cathode where the lead (iV) oxide is oxidised into lead (II) ions.

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