Question

Draw a well labelled diagram of dry cell and explain its construction.

Answer 1

Anode is $Zn$ container and graphite rod surrounded by $Mn{O}_2+carbon$ acts as cathode. A paste of $N{H}_{4}Cl$ and $ZnC{l}_2$ is filled between the electrodes. The cell potential is 1.25 to 1.5 V.
Oxidation at anode:
$Zn\left(s\right)\to Z{n}^{2+}\left(aq\right)+2e^{-}$
Reduction at cathode:
$2Mn{O}_2\left(s\right)+2N{H}_4^{+}\left(aq\right)+2e^{-}\to M{n}_2{O}_3\left(s\right)+2N{H}_3\left(g\right)+H_{2}O$