E° of Cu is + 0.34V while that of Zn is – 0.76V. Explain.
Cu has electronic configuration [Ar] 3d104s1. Formation of Cu2+ involves disturbing a stable 3d10 configuration. So, the reduced form of Cu2+ is more stable than the oxidized form of Cu. Therefore, the value of E° is positive for Cu.
For Zinc, the electronic configuration is [Ar]3d104s2. Removing two electrons gives a stable configuration [Ar]3d10 with completely filled orbitals. So, the oxidized form is more stable than the reduced form. Therefore, the value of E° is negative for Zn