On the Predictive Ability of the New Thermodynamics of Electrolyte Solutions

This work highlights the main elements of the new thermodynamic approach to electrolyte solutions and demonstrates its ability to make predictions for mixed salt systems. After a review of the state of affairs before the measurement of activities of individual ions, experimental set-ups used for these measurements are described and the essential elements of different methods used to reduce the data are discussed. The results of experiments carried to test a possible bias introduced by uncertainty in the values of the junction potential are emphasized. It is purported that the thermodynamic treatment proposed by Lin and Lee is of general application and ensures the thermodynamic consistency of correlations previously proposed for the individual ionic activities. It is shown that the use of a more complex form for the contribution of long-range interactions to ionic activities leads to a simpler form of the osmotic coefficient. As an example of application, the predictions of the equilibrium pressure over NaCl + KCl, NaBr + KBr, and NaCl + CaCl2 aqueous solutions, at different temperatures and compositions. are compared with independently measured experimental data.