`E^(Theta)` of Cu is +0.34V while that of Zn is -0.76 V. Explain.

Explanation

`E^(Theta)` value of Cu is positive because of the fact that sum of sublimation enthalpy and ionisation enthalpy to convert Cu(s) to `Cu^(2+)` (aq) is so high that it is not compensate by its hydration enthalpy. `E^(Theta)` value for Zn is negative because of the fact that after removal of electrons from 4s orbital, stable `3d^(10)` configuration is obtained.