Vapor and Sublimation Pressures of Three Normal Alkanes: C20, C24, and C28

Vapor and sublimation pressures of three n -alkanes C 20, C 24, and C 28 have been determined using a modified gas saturation method. The obtained pressure values range from 10 −5 Pa to 5.5 Pa. From the temperature dependence of the vapor pressures, the molar enthalpies of vaporization and sublimation at the mean temperature of the experimental range were derived from the Clausius−Clapeyron equation. From these results, the standard enthalpies of vaporization and sublimation at T = 298.15 K were calculated.