Question

Give a reason for the following: 

 E° value for (Mn²⁺|Mn) is negative whereas for  (Cu²⁺|Cu) is positive. 

Answer 1

E° value for (Mn²⁺|Mn) is negative whereas for (Cu²⁺|Cu) is positive as the hydration enthalpy of Cu²⁺  ion is not sufficient to compensate the sum of sublimation as well as first and second ionization enthalpy of copper.