Theorem of corresponding states applied to saturated liquids and vapors

The existence of a single generalized compressibility‐factor relationship for univariant systems has long been denied because reduced variables do not provide a generalized vapor‐pressure relationship. The present study demonstrates that a saturation curve depends on the ability of the theorem of corresponding states to correlate the reduced temperature as a function of reduced, pressure and the critical compressibility factor. Saturation curves for both the liquid and the vapor phases are established from compressibility data on a variety of systems, substantiating this conclusion. The compressibility factors of saturated mixtures are correlated with pseudoreduced properties based upon Kay's pseudocritical concept. The results indicate that the compressibility factors of saturated liquid mixtures can be predicted with reasonable precision over the entire two‐phase region. For pseudoreduced isotherms of unity and above, the same isotherms apply to both phases and are approximately consistent with published compressibility charts for pure gases.