Fundamentals of Chemical Engineering Thermodynamics

Chapter 7. VLE of Pure Fluid

At the vapor-liquid boundary, a single-phase system splits into two phases,¹ each with its own properties (molar volume, enthalpy, entropy, etc.). The precise conditions under which phase splitting occurs is an important problem in thermodynamics. Up to this point we have relied on tabulated values and empirical equations, such as the Antoine equation, to establish the relationship between saturation temperature and pressure. In this chapter we develop a connection between the conditions at saturation and the equation of state. The key thermodynamic property that makes this connection possible is the Gibbs energy.

1. A pure substance can form up to three coexisting phases.

The learning objectives for this chapter ...