Radiochemical Measurements of Activity Coefficients in Mixed Electrolytes

Abstract

A method is described for the precise meas~~relnelit of the activity coefficients of salts in mixed electrolytic solutions. I t involves the use of synthetic ion exchange resins and radioactive tracers. The activity coefficients of the chlorides of sodium, potassium, rubidium, and cesium were measured a t effectively zero concentration in hydrochloric acid solutions from 0.005 to 1.5 m. The activity coefficient of sodium chloride in solutions of lithium and potassium chlorides was also determined. The results are discussed in terms of both the Harned rule and the Stolies-Robinson theory of activity coefficients.

Solvation of Ions

“…The results of equilibrium data of HC1 solutions up to 1.7 molal containing radioactive alkali metal chlorides and of LiCl and KC1 solutions containing radioactive Na with synthetic ion exchange resins at 25°C were discussed [400] in terms of the Harned rule and the hydration theory of Stokes and Robinson. Competitive hydration of cations was indicated in mixed electrolyte solutions.…”

Ion Exchange

“…Bonner et al (10,(31)(32)(33) have determined equilibrium constants for several monovalent cation exchange systems using the Gibbs-Duhem relationship. Betts (22) developed a relationship for the exchange of ions in solutions of mixed electrolytes. The equilibrium for the exchange of organic bases with a carboxylic exchanger has been studied by Saunders (245).…”

Ion Exchange

“…Babcock (36) has presented a discussion of free energy relationships in exchange. Application of the ion exchange equilibria theory has been attempted for the purpose of determining activity coefficients of mixed electrolytes (40). Bregman (55) has reported on the equilibria for phosphonic-type cation exchange resins.…”