1.

(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.

Answer»

Solution :(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)`


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