SOME USES AND MISUSES OF THERMODYNAMIC MODELS FOR DILUTE LIQUID SOLUTIONS

Polymer solubility, liquid-liquid solute partitioning, and electrolyte activities are examples of important thermodynamic properties of liquid systems' where components are found at low concentrations in solvents. It is common to analyze solution composition data with expressions such as osmotic virial expansions and/or Debye-Huckel electrostatic models without careful regard for the correct relationship of the coefficients to the molecular solute-solute interactions. The purpose of this work is to (1) note the different thermodynamic variables of solutions, (2) briefly summarize the connections of the coefficients to molecular interactions, (3) demonstrate how the differences are related to experimental values, and (4) illustrate practical cases in phase equilibria of polymeric and ionic solutes.