Volume correction for direct and indirect moving boundary transference measurements

Abstract

A theoretical analysis shows that the volume correction for transference numbers obtained by the direct moving boundary method should be calculated using apparent molar volumes and not, as has been the practice hitherto, partial molar volumes. Various other assumptions and formulae for the volume correction that have been proposed give rise to appreciable errors, particularly where high local concentrations develop as around a dissolving anode. One such case was examined experimentally. Application of the apparent molar volume treatment to the indirect moving boundary method reconciles different equations derived in the literature for the corrected Kohlrausch relation.