Does a solid also have two kinds of molar heat capacities CP and CV? If yes, do we have CP > CV? Is CP – CV = R?
Yes, a solid also has two kinds of molar heat capacities, Cp(at constant pressure) and Cv(at constant volume).
Solids are almost incompressible.
Hence, the values of Cp and Cv are such that Cp > Cv, but they are almost equal since the dependence on heat capacities is very less in the case of solids.
Since the values of Cp and Cv are not that different, Cp - Cv is much less than R.