Real Ionic Solutions in the Mean Spherical Approximation. 1. Simple Salts in the Primitive Model

Abstract

Departures from ideality in electrolytes are described in the framework of the primitive model of ionic solutions in which the solvent is a dielectric continuum, using the mean spherical approximation (MSA). To include solvation and solvent concentration effects, we consider that the permittivity of the solvent and the sizes of the ions are concentration-dependent parameters. New expressions are derived for the activity coefficients and the osmotic coefficient. They are applied to pure ionic aqueous solutions of 18 salts, taking simple functions for the adjusted parameters. Good fittings are obtained in the concentration range 0−6 mol/kg.

Water activities, osmotic and activity coefficients in aqueous chloride solutions atT= 298.15 K by the hygrometric method

“…(11)(12)(13)(14)(15) For electrolytes whose ions associate in solution, the solute activity coefficient remains relatively low as the concentration increases. The effective ion concentration is lowered because the ions are associated.…”

Activity coefficients in sea water using Monte Carlo simulations

“…Based on the assumption that anions are only weakly hydrated (Simonin et al, 1996), the radius of the chloride ion is set equal to its crystallographic radius which allows the calculation of the single-ion hard-sphere radii as shown in Table 2. These values are comparable to those used in the MSA calculations by Vilarino and Sastre de Vicente (1999) and simulations with their radii yield similar results.…”

Corrected Debye–Hückel Analysis of Surface Complexation

“…In a number of studies the MSA has been used to calculate the mean ionic activity and osmotic coefficients of electrolyte solutions in its restricted (68,74) and unrestricted forms (75)(76)(77). In the restricted form of MSA, ions have the same size and the solvent is represented by the dielectric constant whereas in the unrestricted form different sizes are assigned to cations and anions.…”