Density of ethanolic alkali halide salt solutions by experiment and molecular simulation

The density of ethanolic electrolyte solutions of all soluble alkali halide salts (LiCl, LiBr, LiI, NaBr, NaI, and KI) is studied at 298.15, 308.15, 318.15, and 328.15 K at concentrations up to 0.05 mol/mol or 90% of the solubility limit both by experiment and molecular simulation. The force fields used for describing the ions are of the Lennard-Jones (LJ) plus point charge type, the ethanol force field is of the LJ plus partial charges type. All force fields were taken from previous work of our group and were adjusted to properties of aqueous solutions in case of the ions [J. Chem. Phys. 136 (2012) 084501, J. Chem. Phys. 140 (2014) 044504] and to pure component properties [Fluid Phase Equilib. 233 (2005) 134] in case of the solvent. The Lorentz–Berthelot combining rule is used to determine the mixed interactions between the ions and ethanol. The present simulations are hence predictions as no parameters are adjusted to properties of ethanolic electrolyte solutions. The predictions of the reduced density are found to be in good agreement with the experimental data. Furthermore, the radial distribution function of the ethanol sites around the ions, the solvation number and the residence time of ethanol molecules in the first solvation shell, the self-diffusion coefficient of the ions, and the electric conductivity are systematically studied by molecular simulation and compared to experimental data where available.

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