THEORETICAL CALCULATIONS OF THE IONIC STRENGTH DEPENDENCE OF THE IONIC PRODUCT OF WATER BASED ON A MEAN SPHERICAL APPROXIMATION

摘要

A modified version of the restricted primitive model for electrolyte solutions based on the mean spherical approximation (MSA) is applied to estimate the ionic strength dependence of the ionic product of water in aqueous solutions containing different salts, which are commonly used as background electrolytes (NaCl, KCl, KNO3, and NaClO4). The modification involves the use of permittivity of the solvent as concentration-dependent parameter and a single average effective diameter. This is a way of including effects originated from the solvent which do not exist in the primitive model. In the case of potassium nitrate and sodium perchlorate, a complete methodology to calculate the effective diameter and density dependence of the dielectric constant has been proposed and developed. Fits between calculated and experimental pK(w) values are possible over wide concentration ranges using a single adjustable parameter, namely, the average hard core diameter of water. [References: 44]