The E_ M³⁺ / M²⁺ ^o values for Cr , Mn , Fe and Co are -0.41,+1.57,+0.77 and +1.97 V respectively. For which of these metals, the change in oxidation state from +2 to +3 is the easiest?

Step-by-step solution

The oxidation of a metal ion from +2 to +3 state is represented by the half-reaction M²⁺ M³⁺ + e⁻ . The standard electrode potential for this process is given by E_ M²⁺ / M³⁺ ^o = -E_ M³⁺ / M²⁺ ^o . A process is easiest when the standard reduction potential E_ M³⁺ / M²⁺ ^o is the most negative, which corresponds to the most positive oxidation potential E_ M²⁺ / M³⁺ ^o . Comparing the given values of E_ M³⁺ / M²⁺ ^o : For Cr: -0.41 V For Mn: +1.57 V For Fe: +0.77 V For Co: +1.97 V The value for Cr is the most negati