Thermodynamics of n-octane plus hexynes binary mixtures

The vapor pressures of binary mixtures of n-octane + hex-2-yne, or hex-3-yn e and of the three pure components were measured by means of a static devic e at temperatures between 263 and 343 K. Molar excess Gibbs energies G(E) w ere calculated for several constant temperatures, taking into account the v apor phase imperfection in terms of the second molar virial coefficients, a nd were fitted to the Redlich-Kister equation. Calorimetric excess enthalpy H-E measurements for n-octane + hex-2-yne, + hex-3-yne, or + hex-1-yne are also reported at 303.15 K. These data, along with previous vapor-liquid eq uilibrum data for the n-octane + hex-1-yne mixture, are examined on the bas is of DISQUAC, an extended quasichemical group-contribution model. In terms of DISQUAC, the mixtures studied were characterized by only one type of co ntact: aliphatic/alkyne. The interchange coefficients are not available in the Literature, and are estimated in this work. The model consistently desc ribes the excess functions G(E) and H-E of the investigated n-octane + alky nes mixtures. (C) 2000 Elsevier Science B.V. All rights reserved.