Thermodynamic consistency of binary liquid‐vapor equilibrium data when one component is above its critical temperature

Methods are developed for testing binary system phase‐equilibrium data for thermodynamic consistency when the more volatile component is above its critical temperature. The isothermal case with varying pressure and the isobaric case with varying temperature are considered individually. The rigorous form of the Duhem equation is employed rather than the simplified one, which for binary systems is inconsistent with the phase rule. Although derived for the specific case given in the title, the relationships developed are applicable to all conditions of binary systems. Sample calculations illustrating the methods are included.