Question

Explain how an electromotive force is developed in a Leclanche cell?

Answer 1

The setup of a Leclanche cell is shown below:

At the zinc rod, the atoms get ionized and pass into the solution as ${Zn}^{++}$ ions.This leaves the zinc rod with two electrons more making it negatively charged. At the same time, Ammonium chloride splits into ammonia gas, two Hydrogen ions ( ${2H}^{+}$​) and two chloride ions ( ${2Cl}^{-}$​). ${Zn}^{++}$​ ions and ${2Cl}^{-}$​ ions recombine to form zinc chloride.The ${2H}^{+}$​ ions migrate to the carbon rod and make it positively charged. When the carbon and zinc rods are connected by a wire, current flows from carbon to zinc through the wire. The e.m.f.of the cell is about 1.5V.