Theory of Electrolytes: Part 2.—Tests of the Model of Polarisable Spheres, with some Implications for “ Structure ” in Solutions

Abstract

Predictions of the polarised-sphere theory of electrolytes are compared with experimental results for 1:1, 1:2 and 1:3 electrolytes in water. The theory gives a good account of activity coefficients for a large number of electrolytes in dilute solution (κa < 0.5), and the partial molal enthalpies for 1:1 electrolytes are also accommodated. A limited survey of the results for hydrochloric acid in a number of solvents shows the applicability of the theory for a wide range of the dielectric constant. The significance of ion-size parameters is discussed in relation to the polarisation of solvated ions, and further developments of the electrostatic model are considered in the light of present limitations. An outline is given of a new approach to the phenomenon of “structure” in solutions.