For M^(2+)//M and M^(3+)//M^(2+) systems, the E^(@) values for some metals are as follows : {:(Cr^(2+)//Cr,,=-0.9V,,Cr^(3+)//Cr^(2+),,=-0.4V),(Mn^(2+)//Mn,,=-1.2V,,Mn^(3+)//Mn^(2+),,=+1.5V),(Fe^(2+)//Fe,,=-0.4V,,Fe^(3+)//Fe^(2+),,=+0.8V):} Use this data to comment upon : (a) the stability of Fe^(3+) in acid solution as compared to that of Cr^(3+) or Mu^(3+) and (b) the ease with which iron can be oxidised as compared to the similar process for either chromium or manganese metals.

For M^(2+)//M and M^(3+)//M^(2+) systems, the E^(@) values for some me

1.	For M^(2+)//M and M^(3+)//M^(2+) systems, the E^(@) values for some metals are as follows : {:(Cr^(2+)//Cr,,=-0.9V,,Cr^(3+)//Cr^(2+),,=-0.4V),(Mn^(2+)//Mn,,=-1.2V,,Mn^(3+)//Mn^(2+),,=+1.5V),(Fe^(2+)//Fe,,=-0.4V,,Fe^(3+)//Fe^(2+),,=+0.8V):} Use this data to comment upon : (a) the stability of Fe^(3+) in acid solution as compared to that of Cr^(3+) or Mu^(3+) and (b) the ease with which iron can be oxidised as compared to the similar process for either chromium or manganese metals.
Answer» SOLUTION :(a) `CR^(3+)//Cr^(2+)` has a negative reduction potential. Hence, `Cr^(3+)` cannot be reduced to `Cr^(2+)`, i.e., `Cr^(3+)` is most stable. `Mn^(3+)//Mn^(2+)` has large POSITIVE `E^(@)` value. Hence, `Mn^(3+)` can be easily reduced to `Mn^(2+)`, i.e., `Mn^(3+)` is LEAST stable. `E^(@)` value for `Fe^(3+)//Fe^(2+)` is positive but small. Hence, `Fe^(3+)` is more stable than `Mn^(3+)` but less stable than `Cr^(3+)`. Thus, the stability follows the order : `Cr^(3)gt Fr^(3+)gt Mn^(3+)` (b) Oxidation potentials for the given pairs will be `+0.9V,+1.2V` and `+0.4" V"`. Thus, the order of GETTING oxidised will be : `Mn gt Cr gt Fe`