dation Grant ENG 77-15953 is gratefully acknowledged. We thank the Calgon Corp. for providing activated carbon. after initial heat treatment reacted/(kg of virgin carbon unburned) (s) generation, m2 The volumetric and phase behavior of propane-perfluorocyclobutane mixtures has been determined in the critical region. This system exhibits a minimum temperature point in its critical locus curve and forms a positive critical azeotrope. The measured critical points in this system and their correlation using an extended corresponding states principle are reported in this paper.

P‐V‐T‐x data for the propane‐perfluorocyclobutane system are reported in this paper. The data cover a temperature range from 329.4 to 397.7°K and a pressure range from 60 to 6920 kPa. The low pressure compressibility measurements were used to determine second virial coefficients of pure propane and pure perfluorocyclobutane and for seven of their mixtures. The prediction of second virial coefficients using an extended corresponding states principle is also reported. Excellent predictions of the second virial coefficients of both pure components and mixtures have been obtained using, in the case of mixtures, a binary interaction coefficient obtained from a study of the critical states of the system.

Measurement of vapor‐liquid equilibria and azeotropic states of propane‐perfluorocyclobutane mixtures are reported in this paper. The propane‐perfluorocyclobutane system exhibits positive azeotropic behavior which persists in the critical region of the system. The prediction of vapor‐liquid equilibria and of the locus of azeotropic points using an extended corresponding states principle is also reported. The predictions require information obtained solely from a study of the critical states of the system.