Modeling of dilution enthalpies within implicit-solvent models for electrolytes

This work deals with the calculation of dilution enthalpies for strong aqueous electrolyte solutions when their thermodynamic properties are described within implicit-solvent models. The solution is modeled as a collection of charged hard spheres in a continuum solvent. A new general expression is obtained that accounts for the variation of the solution permittivity, of the size of the ions, and of the specific volume of the solution, with temperature and concentration. This expression is used to compute the enthalpies of LiCl aqueous solutions at temperatures in the range of 25∘C to 100∘C for concentrations up to 6 mol kg−1. The mean spherical approximation (MSA) model with implicit continuum solvent is employed to describe the thermodynamic properties of these solutions. •Dilution enthalpies for electrolytes are described within a model with implicit solvent.•The electrolyte is modeled as a collection of charged hard spheres in a continuum solvent.•The model involves a permittivity and ion sizes that vary with concentration and temperature.•General theoretical expressions are obtained for dilution enthalpies in that case.•Data for aqueous LiCl solutions between 25 °C and 100 °C up to 6 molal are modeled using the MSA.