Question

Why electrolysis of molten lead bromide is considered to be a redox reaction?

Answer 1

Hint: A redox reaction is a reaction where both oxidation and reduction takes place simultaneously. During the electrolysis of molten lead bromide, the bromide ions are converted to bromine atoms and the lead ions are converted to lead atoms.

Complete answer:
We know that a reaction where oxidation and reduction takes place simultaneously is known as a redox reaction which is the abbreviation for reduction-oxidation reaction.
We define electrolysis as a process in which we pass electric current through a substance for it to react chemically. Electrolysis involves breaking of electrolytes into ions.
In the process of electrolysis, there is a cathode and an anode. Anode is the negative end and oxidation takes place at the anode and cathode is the positive end and reduction takes place here.
We can write the formula of lead bromide as $PbB{{r}_{2}}$. When molten lead bromide undergoes electrolysis, there are two simultaneous processes which take place at cathode and anode and we can write the reactions of these processes.
At the anode, oxidation takes place. As we know, oxidation means loss of electrons therefore anode becomes the negative end. The bromide ions lose electrons at the anode and become Br-atoms which later pairs up with another Br-atom to give us a bromine molecule. We can write the reaction at anode as-
     \[2B{{r}^{-}}\to B{{r}_{2}}+2{{e}^{-}}\]
At the cathode, reduction takes place. We know that reduction means gain of electrons. The lead ions gain electrons at the cathode and become lead atoms. We can write the reaction at anode as-
     \[P{{b}^{2+}}+2{{e}^{-}}\to 2Pb\]
We can write the net reaction as- $PbB{{r}_{2}}\to P{{b}^{2+}}+2B{{r}^{-}}$
As we can understand from the above discussion, both oxidation and reduction take place during the electrolysis of lead bromide.
Therefore, we can consider electrolysis of lead bromide to be a redox reaction.

Note:
Electrolysis is the process by which water is produced from hydrogen and oxygen gas.
A redox reaction where the same atom undergoes oxidation as well as reduction to give us two different products is known as a disproportionation reaction. In a redox reaction, the transfer of electrons is identified by seeing the change in oxidation number of the species which are reacting.