For M2+/M and M3+/M2+ systems, the E- values for some metals are as follows:
Cr2+/Cr −0.9V
Cr3/Cr2+ −0.4 V
Mn2+/Mn −1.2V
Mn3+ /Mn2+ +1.5 V
Fe2+ /Fe −0.4V
Fe3+/Fe2+ +0.8 V
Use this data to comment upon:
(i) The stability of Fe3+ in acid solution as compared to that of Cr3+ or Mn3+ and
(ii)The ease with which iron can be oxidised as compared to a similar process for either
chromium or manganese metal.
