(a) Standard EMF of the cell, `Cu|Cu 2+| Ag Ag|` is 0.46V at 25°C. Find the value of standard free energy change for the reaction that occurs in the cell.
(b) Draw the neat labeled diagram of SHE and write its symbolic representation.

Explanation

(a) `DeltaG^@ =-nFE^(@)_(cell) `
n = 2, F = 96, `500 C E^@ = 0.46V`
`AG^@=-2xx96,500xx0.46`
`AG^@ = -108080 joules`
`AG^@ = -108.80 KJ`
(b) SHE is a primary reference electrode because its SRP value (E) is zero V.
Construction : It consists of a platinum foil fused to a platinum wire. It 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 1 M 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 HCI. The electrode reaction is as shown below.
`H_(2)(g) to 2H+ +2e^(-)`
So hydrogen electrodes can be represented as Pt(s), `H_(2), ("g, Ibar") | H+ (1M)`