关键词: 质量作用浓度, 活度, 电解质溶液, 共存理论, 转换系数

Abstract: A universal thermodynamic model which can be applied to calculate mass action concentrations of components in strong electrolyte aqueous solutions has been developed in this work based on the ion-molecule coexistence theory. To verify the new universal thermodynamic model, four binary systems, such as KCl-H2O, CsCl-H2O, NaCl-H2O and BaCl2-H2O, are chosen to calculate mass action concentrations of components in a concentration range from 0.2 mol/kg to saturation level at 298.15 K. The present calculated mass action concentrations are based on pure species as standard state and mole fraction as concentration unit. A transformation coefficient is provided to convert the reported activities based on infinite dilution as standard state and mass mole fraction as concentration unit, so that the comparison of the present model with the literature data can be conducted. The transformation coefficients change in a very narrow fluctuation range for each component. The mass action concentrations of components are in good agreement with those of reported activities. Hence, the newly developed universal thermodynamic model can be successfully applied to predict activities of components in other strong electrolyte aqueous solutions and to describe their structure characteristics in aqueous solutions.

Key words: mass action concentration, activity, electrolyte aqueous solution, coexistence theory, transformation coefficient