A fourth parameter for the vapor pressure and entropy of vaporization of polar fluids

Pitzer's acentric factor approach has been extended to the vapor pressure and entropy of vaporization of polar fluids. Normal fluid vapor pressure functions have been determined for 0.44 ≤ TR < 0.56. A polarity factor has been defined and polar correction terms established for the vapor pressure for 0.44 ≤ TR < 0.70 and for the entropy of vaporization for 0.56 < TR < 0.72. The polar correction terms enable the accurate calculation of the vapor pressure and entropy of vaporization of a polar fluid from its normal boiling point and normal latent heat of vaporization. The results of this study also form the basis for the extension of this approach to other thermodynamic properties of polar fluids.