Question

Write the overall reactions taking place at the anode in a lead accumulator cell during discharging of the cell.

Answer 1

When the cell provides current, spongy lead is oxidised to Pb²⁺ ions and negative charge accumulates on lead plates. The Pb²⁺ ions so formed combine with \[\ce{SO^{2-}4}\] ions from H₂SO₄ to form insoluble PbSO₄. The net oxidation is the sum of these two processes.

\[\ce{Pb (s) ->Pb^{2+} (aq) + 2e− (oxidation)}\]

\[\ce{Pb^{2+} (aq) + SO^{2−}4 (aq) → PbSO4 (s) (precipitation)}\]
_________________________________________________

\[\ce{Pb (s) + SO^{2−}4 (aq) → PbSO4 (s) + 2e− (overall oxidation)}\]