The E M 3 + / M 2 + 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 form +2 to +3 is easiest?

Step-by-step solution

E C r 3 + / C r 2 + o = - 0.41 V E M n 3 + / M n 2 + o = + 1.57 V E F e 3 + / F e 2 + o = + 0.77 V E C o 3 + / C o 2 + o = + 1.97 V Reducing nature or tendency to get oxidized ∝ - E r e d o As more negative value of E r e d o indicates better reducing agent thus easily oxidized so oxidation of C r 2 + to C r 3 + is the easiest. Reducing nature for these metals is as follows Cr > Fe > Mn > Co.