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 liqu id systems' where components are found at low concentrations in solven ts. It is common to analyze solution composition data with expressions such as osmotic virial expansions and/or Debye-Huckel electrostatic m odels without careful regard for the correct relationship of the coeff icients to the molecular solute-solute interactions. The purpose of th is work is to (1) note the different thermodynamic variables of soluti ons, (2) briefly summarize the connections of the coefficients to mole cular interactions, (3) demonstrate how the differences are related to experimental values, and (4) illustrate practical cases in phase equi libria of polymeric and ionic solutes.