SUBLIMATION ENTHALPIES AT 298.15 K USING CORRELATION GAS-CHROMATOGRAPHY AND DIFFERENTIAL SCANNING CALORIMETRY MEASUREMENTS

The sublimation enthalpies of 17 hydrocarbons are obtained by combinin g the technique of correlation gas chromatography (CGC), to evaluate v aporization enthalpies at 298.15 K, and differential scanning calorime try (DSC) to measure fusion enthalpies. Vaporization enthalpies at 298 .15 K obtained by CGC are compared to values measured directly from va por pressure measurements at temperatures above the melting point by a djusting the experimental vaporization enthalpy for the effects of tem perature. Vaporization enthalpies obtained by these two methods agree within +/-3877 J mol(-1). Fusion enthalpies are similarly adjusted for temperature. Sublimation enthalpies, obtained by combining temperatur e adjusted fusion, and vaporization enthalpies agree within +/-2580 J mol(-1). The sublimation enthalpies of azulene and 1,8-cyclotetradecad iyne are also measured by head-space analysis resulting in values of 7 6880 and 94348 J mol(-1) at 298.15 K, respectively. (C) 1998 Elsevier Science B.V.