Question

State the observation at the anode and at the cathode during the electrolysis of
Fused Lead bromide using graphite electrodes.

Answer 1

Observations at the anode:-

1. Bromine gas is formed after the bromide ions loses electrons.
2. Dark brown-reddish fumes of bromine gas are obtained at the anode.
3. Reaction at the anode:$\underset{\mathrm{Bromide}\mathrm{ion}}{2{\mathrm{Br}}^{-}\left(\mathrm{aq}\right)}\to \underset{\mathrm{Bromine}}{{\mathrm{Br}}_2\left(\mathrm{g}\right)}+\underset{\mathrm{Electron}}{2{\mathrm{e}}^{-}}$

Observations at the cathode:-

1. the electrons that bromide ion lost are here accepted by the lead ions.
2. As a result greyish-white deposit of lead metal is observed at the cathode.
3. Reaction at the cathode: $\underset{\mathrm{Lead}\mathrm{ion}}{{\mathrm{Pb}}^{2+}\left(\mathrm{aq}\right)}+\underset{\mathrm{Electron}}{2{\mathrm{e}}^{-}}\to \underset{\mathrm{Lead}}{\mathrm{Pb}}\left(\mathrm{s}\right)$

Therefore, dark brown-reddish fumes of bromine gas are observed at the anode and a greyish-white deposit of lead metal is observed at the cathode.