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

Hint: Oxidation reaction occurs at anode. Zinc metal loses two electrons to form zinc cations. Reduction reaction occurs at cathode. In the presence of ammonium ions, manganese dioxide gains electrons. In mercury cells, mercuric oxide and zinc react in presence of an alkali.

Complete step by step answer:
In dry cells, a chemical reaction generates electricity.
In the dry cell, oxidation reaction occurs at zinc anode to form zinc cations. Zinc atom loses two electrons to form zinc cations. Write the oxidation half reaction.
\[{\text{Zn }} \to {\text{ Z}}{{\text{n}}^{2 + }}{\text{ + 2 }}{{\text{e}}^ - }\]
Reduction reaction occurs at graphite cathode. Write the reduction half reaction.
\[{\text{2 NH}}_4^ + {\text{ + 2 Mn}}{{\text{O}}_2}{\text{ + 2 }}{{\text{e}}^ - }{\text{ }} \to {\text{ M}}{{\text{n}}_{\text{2}}}{{\text{O}}_{\text{3}}}{\text{ + 2 N}}{{\text{H}}_3}{\text{ + }}{{\text{H}}_2}{\text{O}}\]
Write the overall cell reaction:
\[{\text{Zn(s) + 2Mn}}{{\text{O}}_{\text{2}}}{\text{(s) + 2NH}}_4^ + {\text{(aq)}} \to {\text{M}}{{\text{n}}_{\text{2}}}{{\text{O}}_{\text{3}}}{\text{(s) + }}{{\text{H}}_{\text{2}}}{\text{O(l) + Z}}{{\text{n}}^{2 + }}{\text{ + 2N}}{{\text{H}}_{\text{3}}}{\text{(g)}}\]
The voltage obtained from the dry cell is 1.5 volts.
List the differences between Dry cell and mercury cell, in the following table.



Additional Information: Electrolyte in the dry cell is in the form of a paste so as to avoid spillage. Electrolyte is an acid dissolved in water, which generates positive ions (cations) and negative ions (anions). Ions move towards oppositely charged electrodes. Electrodes are metal rods immersed in electrolyte.

Note: In dry cells, paste of ammonium chloride electrolyte is used, so that amount of water can be minimized. Due to this dry cell can be used in any orientation without any spillage. This increases the ease of handling and convenience of its usage. Hence, dry cells can be used into portable equipment.