Vapor Pressure and Heat of Vaporization of Molecules That Associate in the Gas Phase

Radomir I. Slavchov, Javor K. Novev, Sebastian Mosbach, Markus Kraft

Index: 10.1021/acs.iecr.7b04241

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Abstract

A model of the temperature dependence of the vapor pressure and the heat of vaporization of liquids whose vapors contain associates is presented for two cases: dimers and linear associates in the gas phase. The results are analytic generalizations of the Clausius–Clapeyron equation, valid with accuracy of 0.1%–1%, as demonstrated with 11 liquids: formic and acetic acids, methanol, ethanol, n-propanol, n-butanol, water, benzene, toluene, heptane, and isooctane. The model involves only readily available handbook parameters: the room-temperature heat of vaporization, vapor pressure, heat capacities, second virial coefficient, and heat of dissociation of the dimers in the gas phase.