par Prigogine, Ilya ;Mathot, Victor ;Desmyter, Aline
Référence Bulletin des Sociétés chimiques belges, 58, 10-12, page (547-565)
Publication Publié, 1949
Article révisé par les pairs
Résumé : Considering an associated solution, e. g. alcohol‐carbon tetrachloride, as a system of monomolecules and associated complexes in equilibrium with one another, it is shown that the thermodynamic properties, particularly activity coefficients, are completely determined by the chemical potentials of the monomolecules only. Using the principle of detailed balancing of elementary processes, it is shown that the following relation holds between the activity coefficients ƒA/ƒB = α where α is the fraction of molecules of the associated constituent which appear as monomolecules. This relation may be checked by comparing thermodynamic measurements of ƒA, and ƒB with values of a obtained from the spectroscopic study of the intensity of the OH monomolecular vibration band. Different statistical models are used for the calculation of the thermodynamic properties of the associated solutions. The results are compared and discussed. The influence of the size and shape of the associated complexes is studied. The calculated results are compared to the experimental ones for the systems (Formula Presented.) In these three cases, the relation ƒA/ƒB = α holds quite fairly. A direct proof is thus given that the deviations from ideality may be justified by the formation of complexes in these systems. In addition, the comparison of the observed activity coefficients and those calculated by the different statistical models used shows that, in concentrated solutions, an important part of the complexes must be formed by two or three dimensional molecular aggregates. A chain‐association alone is not sufficient to interpret the departures from ideality. Copyright © 1949 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim