Question

The acid used in lead storage cell is:
A. Phosphoric acid
B. Nitric acid
C. Sulphuric acid
D. hydrochloric acid

Answer 1

Hint: Lead storage cell is one of the secondary batteries i.e. rechargeable batteries. It is also known as lead acid battery. This is one of the common energy storage devices.

Complete step by step answer: In lead storage batteries, each cell consists of a lead anode (a grid of lead filled with finely divided spongy lead) and a grid of lead packed with lead dioxide as cathode. These electrodes are arranged alternately, separated by thin wooden or fiberglass sheets and suspended in diluted sulphuric acid. Diluted sulphuric acid acts as an electrolyte in lead storage batteries. The acid used in lead storage batteries is sulphuric acid which is 38% by mass.

Additional Information:
Since, it is a secondary battery that means it can be recharged after discharging. The reactions involved during discharging are:
At anode:
$Pb(s) + SO_4^{2 - }(aq) \to PbS{O_4} + 2{e^ - }$ (Oxidation)
At cathode:
$Pb{O_2}(s) + SO_4^{2 - }(aq) + 4{H^ + } + 2{e^ - } \to PbS{O_4} + 2{H_2}O$ (Reduction)
By adding above two reaction we get overall reaction as:
$Pb(s) + Pb{O_2}(s) + 4{H^ + }(aq) + 2SO_4^{2 - }(aq) \to 2PbS{O_4}(s) + 2{H_2}O$
The reaction involved during recharging are shown below:
At cathode:
$PbS{O_4}(s) + 2{e^ - } \to Pb(s) + SO_4^{2 - }(aq)$ (Reduction)
At anode:
$PbS{O_4}(s) + 2{H_2}O \to Pb{O_2}(s) + SO_4^{2 - }(aq) + 4{H^ + }(aq) + 2{e^ - }$ (Oxidation)
On addition of above two reactions we get overall reaction as:
$2PbS{O_4}(s) + 2{H_2}O \to Pb(s) + Pb{O_2}(s) + 4{H^ + }(aq) + 2SO_4^{2 - }$
Hence the correct option is answer C.

Note: During the recharging, the cell is operated like an electrolytic cell, i.e. the electrical energy is supplied from an external source. In this case, the electrode reactions are the reverse of those that occur during discharging.