The temperature variation of the Harned coefficient in the system HCl−NaCl

The Harned coefficient measures the effect of an added electrolyte on the activity coefficient of another electrolyte. It is composite, depending partly on properties of solutions containing only one electrolyte and partly on the magnitude of a coefficient characteristic of interaction between two like charged ions in the mixed electrolyte solution. From the meager data available, the latter coefficient depends little upon temperature. The consequences of assuming temperature independence are discussed.Prepared for publication by R. G. Bates.