Q. 4
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+
Answer :
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.
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Using the standard electrode potentials given in the Table 8.1, predict if the reaction between the following is feasible:
Fe3+(aq) and I–(aq)
NCERT - Chemistry Part-II