Draw the neat lableled diagram of SHE and write its symbolic representation.

Explanation

SHE is a primary reference electode because its SRP value `(E^0)` is zero V.
Construction : It consists of a platinum foil fused to a platinum wire. lt is enclosed in a narrow glass tube. It is surrounded by a cylindrical glass jacket having an inlet at the top and the platinum foil is dipped in 1M HCI solution.
Working : Pass pure and dry hydrogen gas continuously at 1 atm pressure into the HCI solution through an inlet. The hydrogen gas gets adsorbed on the surface of the Pt foil . The absorbed hydrogen is in contact with the `H^+` ions of 1 M HCl.
The electrode reaction is as shown below
`H_2(g) So hydrogen electrodes can be represented as Pt(s), `H_2` , (g,Ibar) `H^+` (1M)