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



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.

1
1