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Solvation enthalpies and heat capacities of n ‐alkanes in four polymer phases by capillary gas chromatography
Author(s) -
Görgényi Miklós,
Héberger Károly
Publication year - 2005
Publication title -
journal of separation science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.72
H-Index - 102
eISSN - 1615-9314
pISSN - 1615-9306
DOI - 10.1002/jssc.200301849
Subject(s) - solvation , chemistry , enthalpy , heat capacity , siloxane , atmospheric temperature range , van der waals force , gas chromatography , molar volume , polymer , thermodynamics , propane , capillary action , organic chemistry , chromatography , molecule , physics
Molar solvation enthalpy (Δ sol H ° 298 ) and molar heat capacity changes (Δ sol C o p ) were determined by gas chromatography for the C 6 –C 12 n ‐alkanes on four preferred stationary phases (100% polydimethyl siloxane, 50% diphenyl‐50% dimethyl polysiloxane, 50% trifluoropropyl methylsiloxane, and polyethylene glycol) in commercial FSOT. Statistical evaluation indicated the temperature independence of Δ sol C ° p in the range 303–393 K. Δ sol H ° 298 depends linearly on the number of carbon atoms in the n ‐alkanes, but no linearity could be established for Δ sol C ° p of higher homologues on polar columns, which may be due to a more ordered state on the liquid phase. The homologues for which a linear temperature dependence exists demonstrated that Δ sol C o p is related linearly to the van der Waals volume and the temperature derivative of the density of the stationary phase. The results are consistent with a simple physical explanation at the molecular level.