ALKALINE BATTERY

ALKALINE BATTERY
It is an improved form of the dry cell. In this zinc act as anode and MnO2 act as cathode. The electrolyte in this cell is KOH (an alkali) and hence the name alkaline battery. This cell derives the power from the reduction of the cathode and the oxidation of the zinc anode.

Cell Reactions
At anode: Zn(s) + 2OH‾(aq) → Zn(OH)2(s) + 2e‾
At cathode: 2MnO2(s) + H2O(l) +2e‾ → Mn2O3 + 2OH‾(aq)

Overall Cell Reaction
Zn(s) +2MnO2(s) + H2O(l) → Zn(OH)2 (s) + Mn2O3 (s)

The emf of this cell is 1.5V. The zinc anode used in this cell is made porous to provide a large electrode area. This leads to the delivery of more current.
It sustains heavy use and has a longer shelf life. So it is called a heavy duty battery. It performs better in cold weather than the other type of batteries.

The main advantages of alkaline battery over dry battery are

(i) Zinc does not dissolve readily in a basic medium.
(ii) The life of alkaline battery is longer than the dry battery, because there is no corrosion on Zn. (iii) Alkaline battery maintains its voltage, as the current is drawn from it.

Uses:
It is used in calculators, watches.