Application of the activity concept in the physical chemistry of slags

Abstract

In metallurgical literature, single ion activity coefficients are often used erroneously. The present analytical study deals with the introduction of the activity concept in the treatment of slag equilibria. It leads to the conclusion that the use of single ion activity coefficients is confusing. They may be used only in an analogous manner as in dilute aqueous solutions of electrolytes,i.e. when there is a large excess of one component which can be considered as the solvent. In this case, by convention, the activity coefficients are expressed in terms of the ideal dilute solution as standard state (Henrian activities). By studying systems (concentrated solutions) with all components having as standard states their pure liquid compounds (Raoultian activities), the use of single ion activities and single ion activity coefficients lead to obvious contradictions and should be avoided.