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A reduced state vapor‐pressure relationship and its application to hydrocarbons
Author(s) -
Reynes Enrique G.,
Thodos George
Publication year - 1962
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690080318
Subject(s) - vapor pressure , chemistry , thermodynamics , hydrocarbon , equation of state , vapour pressure of water , organic chemistry , physics
The Frost‐Kalkwarf vapor‐pressure equation has been modified to include as variables the reduced temperature and pressure of the substance. The resulting relationship was found to contain a universal constant δ = 0.1832 and three other constants α, β, and γ, which are characteristic of the substance. Relationships between α, β, and γ were found to exist, and thus a vapor‐pressure equation was produced which contains only one characteristic contant β and which is capable of predicting vapor pressures of pure substances up to the critical point. This vapor‐pressure relationship has been applied to hydrocarbons of all types, including normal paraffins, isoparaffins, olefins, diolefins, acetylenes, naphthenes, and aromatics. In these calculations values of β were estimated from the molecular structure of the hydrocarbons. For hydrocarbons the approach developed in this study was found to reproduce experimental vapor pressures with an average deviation of 2.7% for 456 experimental points representing fifty four hydrocarbons. This study indicates that if reliable vapor‐pressure data, however meager, are available for a hydrocarbon, these data can be used to obtain constants which enable the prediction of the critical temperature and the critical pressure of the substance.