Improved representation of velocity correlations in aqueous electrolyte solutions

Abstract

A general definition of the salt molecule for any asymmetric polyvalent electrolyte in solution is given which fulfils the requirement that the solute mass flux in the presence of an electric field strength vanishes when referred to the proper representative point of the molecule. Effectively this is the definition of the mass flux in the microscopic representation of an electrolyte solution. The electric current density arising from a gradient in the chemical potential also vanishes when referred to the same representative point. Time integrals over the velocity cross-correlation functions have been calculated for aqueous NaCl, LiCl, CaCl₂ and BaCl₂ solutions using conductivity data, transport numbers and mutual diffusion coefficients fulfilling the above requirements. A first approximation is also given for the calculation of velocity correlation coefficients in the case where transport numbers are not available.