Question

What type of battery is a lead storage battery? Write the anode and cathode reaction and the overall cell reaction occurring in the operation of the lead storage battery.

Answer 1

Hint: Lead storage battery is a rechargeable battery. It can be reused again and again. At the anode, solid lead gets oxidized. At cathode reduction of lead oxide takes place. So, overall two electrons exchanged during the reaction.

Complete answer:
Batteries are of two types:
i) Primary - The primary cell is non-rechargeable batteries.
ii) Secondary - The secondary cells are rechargeable batteries. It can be recharged again by passing current in the opposite direction.

Lead storage batteries can be recharged again, so it is a secondary battery. In lead storage battery anode is made up of lead and the cathode is made up of lead grids packed with lead oxide. The electrolytic solution used in lead storage batteries is percent sulphuric acid.

Reaction at anode is as follows:
Anode solid lead oxidized in presence of sulphuric acid to form lead sulphate and release two electrons.
\[{\text{Pb(s)}}\,{\text{ + }}\,{\text{SO}}_4^{2 - }{\text{(aq)}}\,\, \to \,{\text{PbS}}{{\text{O}}_{\text{4}}}{\text{(s)}}\, + \,2{{\text{e}}^ - }\,\]

Reaction at cathode is as follows:
At the cathode, solid lead oxide is reduced in presence of sulphuric acid to form lead sulphate and water.
\[{\text{Pb}}{{\text{O}}_2}{\text{(s)}}\,{\text{ + }}\,{\text{SO}}_4^{2 - }{\text{(aq)}}\,\, + 4\,{{\text{e}}^ - }\, + \,2\,{{\text{H}}^ + } \to \,{\text{PbS}}{{\text{O}}_{\text{4}}}{\text{(s)}}\, + \,2\,{{\text{H}}_2}{\text{O(l)}}\,\]

The overall reaction is as follows:
\[{\text{Pb(s)}}\,{\text{ + }}\,{\text{Pb}}{{\text{O}}_2}{\text{(s)}}\,{\text{ + }}\,{{\text{H}}_2}{\text{S}}{{\text{O}}_4}{\text{(aq)}}\,\, \to \,2\,{\text{PbS}}{{\text{O}}_{\text{4}}}{\text{(s)}}\, + \,2\,{{\text{H}}_2}{\text{O(l)}}\,\]

Therefore, a lead storage battery is a secondary type of battery.

Note: Primary batteries are used only for once. They become dead after one use. Example of the primary battery is leclanche cell and mercury cell. The primary batteries are used in clocks. Secondary batteries are used in inverters. In a leclanche battery, zinc works as an anode, and carbon wrapped with magnesium oxide works as a cathode. In mercury batteries, zinc-mercury amalgam works as anode carbon with a paste of mercury oxide working as a cathode.