Describe the composition of anode and cathode in a mercury cell. Write the electrode reactions for this cell.

Explanation

Mercury cell: It consists of zinc mercury amalgam as anode, a paste of HgO and Carbon black is used as cathode. The electrolyte is a paste of KOH and ZnO.
At anode : Zn (amalgam) + `2OH^(-) to ZnO(s) + H_2O(l) + 2e^(-)`
At cathode : `HgO(s) to ZnO(s) + Hg(l)`.