Question

Give appropriate scientific reasons for the following statements:
Electrolysis of molten lead bromide is considered to be a redox reaction.

Answer 1

• Electrolysis is the process of breaking the compound into its constituent parts, present in its molten form when an electric current is passed through it.

Step 1: Writing the reaction

The dissociation reaction is,

${\mathrm{PbBr}}_2\left(\mathrm{l}\right)\stackrel{\mathrm{Electrolysis}}{\rightleftharpoons }{\mathrm{Pb}}^{2+}\left(\mathrm{aq}\right)+2{\mathrm{Br}}^{-}\left(\mathrm{aq}\right)$

Step 2: Reaction at the cathode and anode

At the cathode, the reduction will take place. The reaction is,

${\mathrm{Pb}}^{2+}\left(aq\right)+2e^{-}\to \mathrm{Pb}\left(l\right)$

At the anode, oxidation will take place. The reaction is

$2{\mathrm{Br}}^{-}\left(aq\right)-2e^{-}\to {\mathrm{Br}}_2\left(g\right)$

Both oxidation and reduction occur at the same time, therefore the electrolysis of molten Lead Bromide is called a redox reaction.