For M²⁺/M and M³⁺/M²⁺ systems the E⊖ values for some metals are as follows:
Cr²⁺/Cr −0.9V Cr³⁺/Cr2²⁺ −0.4V
Mn²⁺/Mn −1.2V Mn³⁺/Mn²⁺ +1.5V
Fe²⁺/Fe −0.4V Fe³⁺/Fe²⁺ +0.8V
Use this data to comment upon:
(i) the stability of Fe3+ in acid solution as compared to that of Cr³⁺ or Mn³⁺
