Some empirical rules concerning the vapor pressure curve revisited

• A Claussius–Claperyron equation is obtained in the Pitzer corresponding states scheme.
• Some well-known empirical rules for the vapor pressure are rewritten in terms of the Pitzer acentric factor.
• The Guggenheim point follows the corresponding state scheme better than the normal boiling point.
• The Ambrose–Walton vapor pressure equation yields excellent agreement with NIST data in all considered cases.

A form for the Clausius–Clapeyron vapor-pressure equation is obtained in the Pitzer corresponding states scheme. This equation allows one to rewrite the well-known Trouton, Guldberg, van Laar and Guggenheim rules in terms of the acentric factor ω. The original forms of these empirical rules are recovered for some particular values of ω. The proposed rules are checked by analyzing National Institute of Standards and Technology (NIST) data on the liquid-vapor coexistence curve for 105 fluids. These rules have been also analyzed by using the well-known Ambrose–Walton (AW) vapor pressure equation.