Molar excess enthalpies of n‐monohaloalkanes + n‐monohaloalkanes mixtures. Estimation of DISQUAC interchange energy parameters

Abstract

AbstractMolar excess enthalpies, H, at 298.15 K and atmospheric pressure were determined for six binary liquid mixtures [x{iodethane or 1‐iodobutane or bromoethane or 1‐bromobutane or 1‐chloropropane or 1‐chloropentane} + (1 ‐ x) 1‐fluoropentane]. These experimental results along with the data available in the literature on molar excess Gibbs energies, G, activity coefficients at infinite dilution, In γ, and molar excess enthalpies, H, for n‐monohaloalkane + n‐monohaloalkane mixtures, are examined on the basis of the DISQUAC group‐contribution model. The interchange energies of the contacts between two different halogen atoms are entirely dispersive and were determined in this work. The model reproduces reasonably well most of the experimental data. For a given n‐monohaloalkane, mixed with the other n‐monohaloalkanes, it can be seen that the values of the dispersive interchange energies coefficients of the Gibbs energy, C, and enthalpy, C, the contact between the two different halogen atoms, X and Y, and the experimental equimolar values of the excess thermodynamic properties G(x1 = 0.5), and H(x1 = 0.5), have the same trend as the gas‐phase electric dipole moment, p, of the molecule X‐Y. The same trend is also observed for the difference in the electric polarizability, Δα, between the halogen atoms X and Y.