The E°M3+/ M2+ values for Cr, Mn, Fe and Co are – 0.41, +1.57, 0.77 and +1.97 V respectively. For which one of these metals the change in oxidation state from +2 to +3 is easiest?
(a) Cr
(b) Mn
(c) Fe
(d) Co.
(a) : Cr2+ | Cr3+ = +0.41V Mn2+ | Mn3+ = –1.57V Fe2+ | Fe3+ = – 0.77V Co2+ | Co3+ = – 1.97V More is the value of oxidation potential more is the tendency to get oxidised. As Cr will have maximum oxidation potential value,therefore its oxidation will be easiest.
