Homogeneous nucleation temperatures in aqueous mixed salt solutions

Abstract

This is the first report on the measurement of homogeneous nucleation temperature, T_H, in the presence of aqueous mixed salt systems of varying compositions and ionic strengths. The T_H,m (T_H value in aqueous mixed salt system) data for these systems have been analyzed in terms of a simple empirical equation. The T_H,m values in simple aqueous mixed salts like NaCl-KCl can be approximated by linear summation of the products of ionic strength fraction and the T_H values of pure salt solutions at the same ionic strength as that of the mixture. The empirical parameter, q⁰, indicating ionic interaction is related to the viscosity B-coefficients. The T_H,m data, though correlated on the basis of the B-coefficients also depends upon the mixing of two ions of like charges. Further, a linear correlation exists between the q⁰ parameter and self-diffusion coefficient, D⁰, of the ionic solute. The q⁰ parameter is also well correlated with the rotational correlation time, t_c^h/t_c⁰ of the ionic species involved in the mixtures. It is possible to compute T_H,m for the salt mixtures with no common ions from the knowledge of the T_H,m values of the salt mixtures with common ions.