Question

Write the chemistry of recharging lead storage batteries highlighting all the materials that are involved using recharging.

Answer 1

Hint: The recharging reaction of the lead storage battery is the exact opposite of the discharging reaction.

Complete step by step answer:
Lead storage battery, also known as lead acid battery is the oldest type of rechargeable battery and is commonly used in automobiles and inverters.
It consists of a lead anode and a grid of lead packed with lead dioxide (PbO2) as cathode. A \[38\% \] solution of sulphuric acid is used as an electrolyte. It can store a lot of charge and provide high current for short periods of time. A good lead storage battery is capable of being recharged by passing current through the battery in the reverse direction so that it can be used again.
In lead storage batteries, when ${H_2}S{O_4}$ is used up during the discharge, the density of ${H_2}S{O_4}$ falls. When it falls below 1.20 $c{m^{ - 3}}$ , the battery needs recharging.
During recharging, the cell is operated like an electrolytic cell, now electrical energy is supplied to it from an external source. The molecules of the Sulphuric acid break up into ions of \[2{H^ + }\] which moves towards the cathode and \[S{O_4}^ - \] which moves towards the anode reacts with lead sulphate.
The electrode is the reverse of those that occur during discharge:
At anode,
 $pbS{O_4}(S) + 2{e^ - } + {H^ + }(aq) \to pb(s) + HS{04^ - }(aq)$ (Oxidation takes place)
At cathode,
 $pb{O_2}(l)2{H_2}O(I) \to pb{o_2}C + HSO{4^ - } + 3{H^ + }(aq) + 2{e^ - }$ (Reduction takes place)
When the above two reactions are combined, the Overall Reaction:
 $2pbS{O_4}(s) + 2{H_2}O(I) \to pb(s) + pbO(s) + 2{H^ + }(aq) + 2HSO{4^ - }(aq) $

Note: On recharging the battery, the reverse reaction of discharging takes place. The products of the reaction at anode and cathode are insoluble which means the substances are available to participate in the opposite reaction that will recharge the battery.