Question

What particles are present in pure lead bromide. write the equations for the reaction that takes place at the electrodes during the electrolysis of lead bromide.

Answer 1

Electrolysis of lead bromide

The particles present in pure lead bromide are lead ions ${\mathrm{Pb}}^{+2}$ and bromide ions ${\mathrm{Br}}^{-}$.

Electrode reactions

At the Cathode

• The Reduction of half-reaction is taking place at the cathode
• The cathode is an electron donor hence the lead ions gain electrons from the cathode to form metallic lead ions.
• Product at the cathode: Lead. silver grey metal(lead) is deposited around the cathode

${\mathrm{Pb}}^{+2}+2{\mathrm{e}}^{-}\to \mathrm{Pb}$

At the anode

• The Oxidation half-reaction is taking place at the cathode.
• Bromide ions give up electrons to the anode and then turn into neutral bromine atoms hence the neutral bromine atoms form covalent bromine molecules.
• Product at the anode: Bromine. Reddish-brown vapors are seen at the anode and then bromine vapors are evolved from the molten lead bromide.

$$\begin{gathered} {\mathrm{Br}}^{-}-{\mathrm{e}}^{-}\to \mathrm{Br} \\ \mathrm{Br}+\mathrm{Br}\to {\mathrm{Br}}_2 \end{gathered}$$