Solvation and chemical engineering thermodynamics

With the continued advances in computational chemistry, solvation calculation from first principle methods is becoming a promising route for phase equilibrium modeling. However, except in a few instances, such an approach has not been widely adopted, which may be a consequence of the abstractness of solvation itself and also of the lack of a simple bridge between solvation and other thermodynamic properties. Here, we establish and summarize the relationship between solvation and other properties frequently used in phase equilibrium modeling. An important quantity, called the total solvation free energy, is introduced so that one can easily derive engineering thermodynamic models (such as an equation of state) from solvation models, or vice versa. The equations presented here are of general validity and would be useful for obtaining existing model parameters from solvation calculations and for developing new models stemming from the ideas of molecular solvation.