Beyond the Virial Expansion: Microscopic Origins of Partial Molar Volumes in LiCl Solutions

The corresponding ionic and water volumes from this treatment quantitatively reproduce the experimental PMV curve, showing that the PMV for salt increases (while water decreases) up to 6.7 M. Above this concentration, the direction reverses as three- and four-body interactions become prominent. Complementary multivariate curve resolution (MCR) Raman spectroscopy and density functional theory (DFT) calculations elucidate the molecular-level details of water electrostriction, which also persists up to 6.7 M. Significantly, the PMV data can be correlated with key thermodynamic properties, including osmotic coefficients and the eutectic point.

The procedures established here provide a general framework for modeling electrolyte solutions and enable the development of a new generation of accurate force fields for aqueous ions.