Question

Give a reason for the following

Electrolysis of molten lead bromide is considered to be a reaction in which oxidation and rection go side by side, that is a redox reaction.

Answer 1

During the electrolysis of lead bromide, there is a loss of electrons at the anode by the bromine ion, that is oxidation takes place there.

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.

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

And there will be a gain of electrons by the lead ion and oxidation takes place.

At the Cathode

• The Reduction 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

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

Hence both reduction and oxidation take place simultaneously, It could be called a redox reaction.