Question

Comment on the following observation:

E^⊝ for \[\ce{M^{2+}_{(aq)} + 2e– -> M(s)}\] (where M = Ca, Sr or Ba) is nearly constant.

Answer 1

Electrode potential (E°) of any M²⁺/M electrode depends upon three factors:

1. Ionisation enthalpy
2. Enthalpy of hydration
3. Enthalpy of vaporisation

The combined effect of these factors is approximately the same for Ca, Sr, and Ba. Hence, their electrode potentials are nearly constant.