Write short note on dry cell.

Explanation

Dry cell: It consits of a cylinderical vessel made of zinc. It is filled with a paste of `NH_(4)Cl` to which a little zinc chloride is added. The zinc cylinder acts as anode (negative electrode). A carbon rod in the centre of the cell serves as the cathode (positive electrode). the cathode is surrounded bya black paste of manganese dioxide, `MnO_(2)` and carbon.
When the cell is working, zinc loses electrons to give `Zn^(2+)` ions. the electrons pass around the external circuit and are taken up at the cathode. this causes discharge of `NH_(4)^(+)` ions. the reaction taking pace at the electrodes are quite complex. however,, they can be represented approximately as follows.