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A molecular theory of the activity coefficients and their reference fugacities at the supercritical state / Stephen G. Martz in Industrial & engineering chemistry research, Vol. 47 n°15 (Août 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 n°15 (Août 2008) . - p. 5016–5022 Titre : A molecular theory of the activity coefficients and their reference fugacities at the supercritical state Type de document : texte imprimé Auteurs : Stephen G. Martz, Auteur ; Lloyd L. Lee, Auteur Année de publication : 2008 Article en page(s) : p. 5016–5022 Note générale : Bibliogr. p. 5022 Langues : Anglais (eng) Mots-clés : Mixtures  --  activity  coefficient  Molecular  theory  Ornstein-Zernike  equations Résumé : We take advantage of the recent advances in statistical mechanics on mixtures to examine a century-old problem in solution thermodynamics, specifically for the popular activity coefficient model, with regard to the absence of a standard state for the noncondensable gases in the mixture. This defect is traced back to the excess Gibbs free energy formalism where insistence on a pure liquid-state reference fluid is incorporated. By examining the molecularly derived counterparts, we propose a new division of the component chemical potential along the line of the molecular theory. A new definition of a reference fugacity and that of a molecular-inspired activity coefficients are formulated to cure this defect. We employ the Ornstein—Zernike equations to actually evaluate the molecular activity coefficients for a mixture of methane and n-pentane. The system temperature is 444 K. Thus, methane is the suprecritical component and does not fit into the classical activity coefficient model. We demonstrate that the molecular activity coefficients of methane and n-pentane can be evaluated and do not suffer nonexistence. Furthermore, these values are used to determine the dew point and bubble point of the mixture. The results compare favorably with the experimental data of Sage and Lacey. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071216d [article] A molecular theory of the activity coefficients and their reference fugacities at the supercritical state [texte imprimé] / Stephen G. Martz, Auteur ; Lloyd L. Lee, Auteur . - 2008 . - p. 5016–5022. Bibliogr. p. 5022 Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 n°15 (Août 2008) . - p. 5016–5022 Mots-clés : Mixtures  --  activity  coefficient  Molecular  theory  Ornstein-Zernike  equations Résumé : We take advantage of the recent advances in statistical mechanics on mixtures to examine a century-old problem in solution thermodynamics, specifically for the popular activity coefficient model, with regard to the absence of a standard state for the noncondensable gases in the mixture. This defect is traced back to the excess Gibbs free energy formalism where insistence on a pure liquid-state reference fluid is incorporated. By examining the molecularly derived counterparts, we propose a new division of the component chemical potential along the line of the molecular theory. A new definition of a reference fugacity and that of a molecular-inspired activity coefficients are formulated to cure this defect. We employ the Ornstein—Zernike equations to actually evaluate the molecular activity coefficients for a mixture of methane and n-pentane. The system temperature is 444 K. Thus, methane is the suprecritical component and does not fit into the classical activity coefficient model. We demonstrate that the molecular activity coefficients of methane and n-pentane can be evaluated and do not suffer nonexistence. Furthermore, these values are used to determine the dew point and bubble point of the mixture. The results compare favorably with the experimental data of Sage and Lacey. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie071216d