Why is the value of standard electrode potential of Mn, Co,Ni,Zn more negative than expected?

Is  the standard electrode potential more negative than expected for cobalt?   (according to graph pg217 NCERT chemistry)

 

Asked by prakriti12oct | 15th Feb, 2020, 08:21: PM

Expert Answer:

Metals will easily lose electrons and oxidised.
Negative electrode potential value means oxidised species is more stable than reduced species.
Mn and Zn have half filled and completely filled d orbitals. It gives them stability and not get reduced.
 
Ni has high negative hydration enthalpy.
 
Therefore the value of standard electrode potential of Mn, Zn, Ni is more negative.

Answered by Varsha | 16th Feb, 2020, 12:32: AM