chapter  9
53 Pages

The Behavior of Solutions

ByDavid R. Gaskell

Condensed phases do have interactions existing among their constituent atoms, molecules, or ions. The nature and magnitudes of these interactions have a significant influence on the thermodynamic behavior of the solution. Solution thermodynamics is concerned with the vapor pressure–temperature–composition relationships of the components of a solution. This chapter examines the solution thermodynamics in more detail. The components of a solution which obeys Raoult's law are said to exhibit Raoultian behavior. The statistical model predicts tendency toward Raoultian behavior and Henrian behavior. In the case of solutions with ordering tendency, the model for both the molar enthalpy and molar entropy of formation can be improved by adding a long-range order parameter (LRO) parameter to the molar enthalpy and molar entropy terms. The variation of the molar excess Gibbs free energy of mixing can give rise to asymmetric dependence of the molar properties of formation.