Vapor Equilibrium at Constant Temperature

In this section we consider a two-component, two-phase liquid-vapor system at constant temperature. We assume that the liquid phase 1 and the vapor phase 2 are ideal. Hence, 022 = 922 = 1 and = RT/p. In addition, we assume that the pressure is low so that and Under these conditions, Eqs. (9-59) 

In order to evaluate the constants of integration in Eq. (9-98) we investigate its values for pure components 1 and 2. When X2 = 0, Eq. (9-98) becomes 

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