Computation of dielectric constants of solvent mixtures and electrolyte solutions

A general model has been developed for calculating the static dielectric co nstant of mixed-solvent electrolyte solutions. For mixtures of solvents wit hout electrolyte components, the model is based on an empirical modificatio n of the Kirkwood theory for multicomponent systems. For systems containing electrolytes, the model takes into account the effects of ions and ion pai rs and, therefore. it is capable of reproducing the dependence of the diele ctric constant on electrolyte concentration. For most solvent mixtures, die lectric constants can be reasonably predicted using only pure solvent prope rties. In the case of strongly nonideal solvent mixtures, the results can b e significantly improved by adjusting a single binary parameter. The model has also been verified for a number of electrolyte solutions in various sol vents over wide composition and temperature ranges. In particular, the incr ease in the dielectric constant due to ion pairing and its decrease due to the presence of ions and their solvation can be accurately represented. (C) 2001 Elsevier Science B.V. All rights reserved.