A Very Precise Canonical Ensemble Monte Carlo Determination of Thermodynamic Properties and of Radial Distribution Functions and Electric Potentials Around Ions in a Primitive Model of 2M Mixtures of KCl and KF at 25°C

Abstract

Abstract Long-run Canonical Ensemble Monte Carlo Simulations (up to 30 million configurations) of a primitive model KCl-KF electrolyte mixture at a total concentration 2 M and at 25°C have been performed for a wide range of the number of ions (N) in the simulation cell (from N = 16 up to N = 1728) and for a number of ratios between the two salt concentrations. The excess energy, the excess heat capacity and the single ion activity coefficients have been simulated directly. The excess osmotic pressure is calculated as a function of salt fraction. A pseudo-ideal point is found for a specific salt fraction, where the osmotic pressure has the ideal van't Hoff value. The previously found analytical correction of the Widom method for the deviation from electroneutrality is used for the single ion activity coefficients. Single “ion” activity coefficients are also simulated for “ions” of the same sizes, but without charge. The results are compared to Mean Spherical Approximation and to Carnahan-Starling-Mansoori ...