Q. 335.0( 2 Votes )
Why E values for Mn, Ni and Zn are more negative than expected?
A negative E value means that the oxidized species is more stable than the reduced species, the metals will easily lose their electrons and get oxidized. Here, Mn2+(3d5) and Zn2+(3d10) have half-filled and fully filled d orbitals which gives them stability and therefore prefer to stay that way and not get reduced. As for Ni2+(3d8), it has very high negative hydration enthalpy which gets balanced by first and second ionization enthalpy.
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