Activity coefficients of KCl and ionic interactions in the system KCl–Me4NCl–H2O at 25, 35 and 45 °C

Abstract

The activity coefficients of KCl in aqueous KCl–Me₄NCl have been determined from emf measurements using a potassium ion-selective electrode and an Ag/AgCl electrode at four values of the total ionic strengths, 0.5, 1.0, 2.0 and 3.0 mol kg^–1 at 25, 35 and 45 °C. The values of log γ_KCl were found to vary linearly with the ionic strength fraction of the second electrolyte, in accordance with the ‘Harned rule’. This indicates that the thermodynamic properties of these mixtures are determined primarily by binary interactions of the type K–Me₄N. The results are discussed in light of the Pitzer, Scatchard and Reilly–Wood–Robinson treatments.