Solubility. III. Relative values of internal pressures and their practical application

Abstract

Various independent methods for calculating internal pressures of liquids are reviewed, and though the values they yield differ considerably, they are seen tobe closely parallel. Pending a theoretical critique of the subject tables of relative internal pressures of relatively nonpolar substances are given for the sake of their practical value. Other substances may be placed with reference to those already given by knowing their densities (as pure liquids or in solution), together with either surface tension; boiling point; the constant a in the van der Waals equation (which may be calculated from critical data or from the atomic values given by van Laar); the coefficient of expansion; or this last, together with the compressibility. The use of these values is discussed in connection with predictions concerning the solubilities of solids, liquids and gases; the distillation of liquid mixtures; molecular weights and “association;” deviations from the mass law; partition coefficients; and the choice of solvent in recrystallization. © 1919, American Chemical Society. All rights reserved.