shows the difference in the thermodynamic concepts of Gibbs and Hildebrand. They divided total molar cohesive energy (enthalpy) into different segments. Gibbs defined the enthalpy as the product of the temperature and the entropic term ∆S. Hildebrand defined the enthalpy as the sum of RT and the temperature-independant term δ 2 V . We combined both these approaches, namely, combine Eq. 9, (which is derived from Eq. 7), with Eq.20.