Nonaqueous solutions osmotic coefficients

The expression (28) has been successfully applied to the description of the osmotic coefficients for different nonaqueous electrolyte solutions with solvent dielectric constant in the range 20< e <36 [6, 14], when ion diameters are treated as adjustable parameters. Examples of the AMSA calculations of the osmotic coefficients for electrolyte solutions are given in Fig. 1 [14]. 

Barthel J, Neueder R, Poepke H, Wittmann H (1999) Osmotic coefficients and activity coefficients of nonaqueous electrolyte solutions. Part 2. Lithium perchlorate in the aprotic solvents acetone, acetonitrile, dimethoxyethane, and dimethylcarbonate. J Solution Chem 28 489-503... 

As far as specific ion effects in nonaqueous solutions (including Ionic Liquids) are concerned, the literature is scarce and no general conclusions have been drawn so far. Mostly, solubility data are given and sometimes also conductivity or osmotic coefficients. A collection of data can be found in [25], but there is no review on specific if effects in nonaqueous systems. 

In this chapter some aspects of the present state of the concept of ion association in the theory of electrolyte solutions will be reviewed. For simplification our consideration will be restricted to a symmetrical electrolyte. It will be demonstrated that the concept of ion association is useful not only to describe such properties as osmotic and activity coefficients, electroconductivity and dielectric constant of nonaqueous electrolyte solutions, which traditionally are explained using the ion association ideas, but also for the treatment of electrolyte contributions to the intramolecular electron transfer in weakly polar solvents [21, 22] and for the interpretation of specific anomalous properties of electrical double layer in low temperature region [23, 24], The majority of these properties can be described within the McMillan-Mayer or ion approach when the solvent is considered as a dielectric continuum and only ions are treated explicitly. However, the description of dielectric properties also requires the solvent molecules being explicitly taken into account which can be done at the Born-Oppenheimer or ion-molecular approach. This approach also leads to the correct description of different solvation effects. We should also note that effects of ion association require a different treatment of the thermodynamic and electrical properties. For the thermodynamic properties such as the osmotic and activity coefficients or the adsorption coefficient of electrical double layer, the ion pairs give a direct contribution and these properties are described correctly in the framework of AMSA theory. Since the ion pairs have no free electric charges, they give polarization effects only for such electrical properties as electroconductivity, dielectric constant or capacitance of electrical double layer. Hence, to describe the electrical properties, it is more convenient to modify MSA-MAL approach by including the ion pairs as new polar entities. 

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See also in sourсe #XX -- [ ]

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