Question

Write anode and cathode reactions that occur in dry cell. How does a dry cell differ from a mercury cell?

Answer 1

The reactions during the discharge of dry cell are-

At anode:- $Zn⟶{Zn}^{+2}+2e^{-}$

At cathode:- $Mn{O}_2+{N{H}_4}^{+}+e^{-}⟶MnO\left(OH\right)+N{H}_3$

The difference between Dry cell and Mercury cell are as follow:

• A dry cell has a very short life span due to the conversion of zinc to zinc chloride that makes the zinc casing porous while in case of mercury cell, the overall reaction does not involve the formation of an ion in the solution whose concentration can change during its lifetime.
• In a Dry cell, we use Zn as an anode while in Mercury cell we use Zn-amalgam as an anode.