The ion interaction approach developed by Pitzer allows the prediction of various thermodynamic characteristics of multiple-solute electrolyte solutions, if the respective parameters for each type of single-solute electrolyte solution are known. The present paper discusses the Pitzer approach to the calculations of the volumetric properties of single-solute electrolyte solutions. The databases for the densities and the apparent molal volumes versus concentrations were created at 298.15 °K using essentially all published relevant data for each single-solute electrolyte solution. Poor experimental data were discarded by a statistical treatment applied to these databases. Proper treatment of all good quality density and apparent molal volume data, in a wide range of concentrations from infinite dilution through saturation, allowed us to evaluate the volumetric ion interaction parameters (V̄0MX, βMX(0)V, βMX(1)V, βMX(2)V, and CMXV) at 298.15 °K for 102 electrolytes. Strong linear relationships between the βMX(1)V, βMX(2)V, or CMXV, and βMX(0)V volumetric ion interaction parameters were observed for all analyzed solutes with slopes depending on the solute valency types.

All existing indirect methods for the separation of A, values into ionic components in organic solvents are analysed. A general method, based on the phenomenon of the non-solvation of large tetraalkyl(ari1)onium ions, is proposed. The method is shown to be independent of the chemical nature of organic solvents and temperature. This permits us to examine the relationship between ionic limiting equivalent conductances and values calculated on their basis, and the intrinsic structure of organic solvents.By using this method, the ionic limiting equivalent conductances are calculated for 50 organic solvents at 25 *C and for 9 solvents over a wide temperature interval. The use of the method for obtaining ionic limiting equivalent conductances in organic mixtures is demonstrated. The values calculated by the suggested method under various conditions are in good agreement with the experimental literature values.

The ion interaction approach developed by Pitzer allows the prediction of thermodynamic characteristics of mixed electrolyte solutions at various temperatures, if the respective parameters for each type of single electrolyte solution are known. Among such thermodynamic characteristics are the volumetric ones (density and apparent molal volumes). A database for the densities and the apparent molal volumes versus concentrations was developed at a temperature interval of 288.15–368.15 K using all available literature sources for each single electrolyte solution formed by various electrically neutral combinations of the following ions (Na+, K+, Mg2+, Ca2+, Sr2+, Ba2+, Cl−, Br−, HCO3−, CO32−, and SO42−). These are the most important ions for industrial solutions as well as for natural waters. Statistical treatment was applied to this database in order to discard poor data. The proper treatment of all sound quality apparent molal volumes, in a wide range of concentrations from infinite dilution through saturation, allowed us to compute sets of volumetric ion interaction parameters (V̄MX0, βMX(0)V, βMX(1)V, βMX(2)V, and CMXV) at various temperatures in a 288.15–368.15 K temperature interval. The validity of the selected sets at various temperatures was demonstrated by a comparison of the experimental and calculated densities for multiple-solute electrolyte solutions containing NaCl, KCl, MgCl2, and CaCl2 with an ionic strength reaching 9.23 that resembled Dead Sea water.

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