Solvation enthalpies and heat capacities of n ‐alkanes in four polymer phases by capillary gas chromatography

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.