Collect. Czech. Chem. Commun. 1980, 45, 1447-1455

Heats of mixing prediction of binary solutions of homologues based on the solution of groups concept

Vladimír Dohnal, Robert Holub and Jiří Pick

Department of Physical Chemistry, Prague Institute of Chemical Technology, 166 28 Prague 6


A relation has been derived, on the basis of the solution of groups concept, for predicting partial molar excess enthalpies or activity coefficients of a system A + B' from experimental data for a related system A + B, requiring no knowledge or adjustment of group contributions. The method suggested has been employed for predicting hE of systems formed by compounds of the same homologous series. For these systems a relation has been derived between constants of the Redlich-Kister polynomial of the basal and predicted systems which makes it possible to obtain directly an easy estimate of these constants for the predicted system. The method has been tested with 20 mixtures of n-alcohols and 25 mixtures of 2-ketones. In the case that the component B' lies in the homologous series between the components A and B the method makes possible the prediction of hE with sufficient accuracy (on the average better than 8%). In the opposite case, providing that the numerical stability of the calculation is ensured, the method provides reliable results only for a slight extrapolation outside the range of components A and B.