Using the standard electrode potential, find out the pair between which redox reaction is not feasible.

E°Values: Fe³⁺/ fe²⁺ = +0.77; I₂/I^- = +0.54;

Cu²⁺/ Cu = -0.34; Ag⁺ /Ag = + 0.80 V

A. Fe³⁺ and I^-

B. Ag⁺ and Cu

C. Fe³⁺ and Cu

D. Ag and Fe³⁺

Feasibility of a redox reaction is decided by the electric potential of the cell made out of two elements. So the net E°_cell for the cell should be positive. The relative position of Ag and Fe³⁺ in electrochemical series and the reduction potential of cell should be determined for all cases.

(i)

The

Since the value is positive the reaction proceeds spontaneously and is feasible.

∴ We can calculate for remaining three reduction potential similarly,

(ii)

(iii)

(iv)

Since the value of potential of cell for Ag and Fe³⁺ is negative we can say that the reaction is non-spontaneous and is not feasible as the redox reaction resists undergoing changes under mentioned configuration of Ag which undergoes oxidation, as its emf is less as compared to Fe³⁺, it readily undergoes reduction. Thus reaction in Option (iv) is not feasible.