Temperature Dependence of the Density of Aqueous Alkali Halide Salt Solutions by Experiment and Molecular Simulation

The density of aqueous alkali halide salt solutions is studied experimentally at 293.15 K, 303.15 K, 313.15 K, 323.15 K, and 333.15 K at 1 bar for solutions containing all soluble combinations of alkali cations (Li+, Na+, K+, Rb+, and Cs+) with halide anions (F-, Cl-, Br-, and I-) at salt concentrations up to 0.05 mol.mol(-1). The temperature dependence of the density of the electrolyte solutions is also determined by molecular simulation in the same temperature and composition range. The force fields of the ions are taken from previous work of our group [J. Chem. Phys. 2012, 136, 084501; J. Chem. Phys. 2014, 140, 044504] and consist of one Lennard-Jones site and a point charge. Water is modeled with the SPC/E force field. A very good agreement between the predictions from molecular simulation and the experimental data of the reduced density is found. In addition, the temperature dependence of the radial distribution function of water around the ions, the hydration number and the residence time of water molecules in the first hydration shell, the self-diffusion coefficient of the ions and the electric conductivity are systematically studied by molecular simulation and compared to experimental literature data where available.