Netsu Sokutei, 44 (4), p. 157, (2017)



Excess Enthalpies of Binary Mixtures in Liquid State, near the Critical Points and Gas State

The excess enthalpy HEm is important in order to understand the mixed state of fluids and intermolecular interaction. The behaviors of HEm of a binary mixture in the liquid state, near the critical points and gas state are quite different each other. In this article, the characteristics of the behaviors of HEm in each state are summarized briefly, and the cause of the difference in each characteristic is discussed in terms of the difference of the main factor of intermolecular interactions affecting the behavior of HEm. At first, the behaviors of HEm of binary mixtures containing aromatic or alcoholic molecular are described. The influences of the π-π interaction and the hydrogen bond on HEm are discussed over a wide range of temperature and pressure in the liquid state. Next, the specific behavior of HEm at near the critical points are discussed with respect to the relation of the experimental states of HEm to the location of the critical points, the vapor pressure curves and their extended curves of component fluids on the p-T plane. Finally, The contribution of the dipole moment and the polarizability of component molecules to the behaviors of HEm at gas state is discussed by comparing HEm of polar molecules + benzene or cyclohexane mixtures.