# Write the chemistry of recharging the lead storage battery,

Question:

Write the chemistry of recharging the lead storage battery, highlighting all the materials that are involved during recharging.

Solution:

A lead storage battery consists of a lead anode, a grid of lead packed with lead oxide (PbO2) as the cathode, and a 38% solution of sulphuric acid (H2SO4) as an electrolyte.

When the battery is in use, the following cell reactions take place:

At anode: $\mathrm{Pb}_{(s)}+\mathrm{SO}_{4}^{2-}(a q) \longrightarrow \mathrm{PbSO}_{4(s)}+2 \mathrm{e}^{-}$

At cathode: $\mathrm{PbO}_{2(s)}+\mathrm{SO}_{4(\text { (aq) })}^{2-}+4 \mathrm{H}^{+}{ }_{(\text {(aq) })}+2 \mathrm{e}^{-} \longrightarrow \mathrm{PbSO}_{4(s)}+2 \mathrm{H}_{2} \mathrm{O}_{(n)}$

The overall cell reaction is given by,

$\mathrm{Pb}_{(s)}+\mathrm{PbO}_{2(s)}+2 \mathrm{H}_{2} \mathrm{SO}_{4(a q)} \longrightarrow 2 \mathrm{PbSO}_{4(s)}+2 \mathrm{H}_{2} \mathrm{O}_{(i)}$

When a battery is charged, the reverse of all these reactions takes place.

Hence, on charging, $\mathrm{PbSO}_{4(s)}$ present at the anode and cathode is converted into $\mathrm{Pb}_{(s)}$ and $\mathrm{PbO}_{2(s)}$ respectively.