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Abstract

A model that relates acentric factors to molecular energies of very small ensembles is developed. Saturation properties are taken from the literature, and energies are calculated using tools of Computational Chemistry. For n-alkanes, the acentric factor is given directly as a linear function of the saturated liquid and vapor phase energies at the ``omega temperature'' defined as 70% of the critical temperature. For other fluids, a perturbation analysis suggests that acentric factor deviations from the behavior of n-alkanes depend on one additional characteristic parameter. Best results are obtained by defining this parameter in terms of the compressibility factors of the saturated phases at that same temperature. The final correlation reproduces the acentric factors of all fluids tested with coefficient of determination R²= 0.9857 and average absolute deviationAAD = 0.0112.

Keywords

Acentric factor,molecular energies,correlation,computational chemistry

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Interpretation and correlation of acentric factors in terms of molecular energies

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