Generalized isothermal transport coefficients of ZnCl 2-H 2O at 25°C

Abstract

Existing transport data for aqueous ZnCl 2 at 25°C have been critically reviewed from 0 to 5 molar. These data, together with previously reviewed activity data, have been used to calculate three sets of generalized transport coefficients: the solvent-fixed ionic Onsager coefficients I ij/N; the Friedman distinct diffusion coefficients D ij d; and the Hertz velocity correlation coefficients f ij. These coefficients for ZnCl 2 are contrasted with the analogous coefficients for aqueous MgCl 2, a model strong electrolyte. Although also known from other evidence, all three sets indicate very clearly that ZnCl 2 behaves as a strong electrolyte to about 0.1 molar. Cation-anion interactions then rapidly become very large, which corresponds to strong ZnCl complexing. There are puzzling aspects of the interpretation of the D ij d and the f ij; the I ij/N seem more intuitively understandable.