Excess Chemical Potentials, Excess Partial Molar Enthalpies, Entropies, Volumes, and Isobaric Thermal Expansivities of Aqueous Glycerol at 25 deg C

摘要

The vapor pressures p the excess partial molar enthalpies of glycerol H~E_(Gly) the densities d and the thermal expansivities #alpha#_p of aqueous glycerol were measured at 25 deg C. From the vapor pressure data, the excess chemical potential of H_2O #mu#~E_W was calculated, assuming that the partial pressure of glycerol p_(Gly) is negligibly small. The excess chemical potential of glycerol #mu#~E_(Gly) was estimated by applying the Gibbs-Duhem relation and these data were used to calculate the excess partial molar entropies S~E_(Gly). From the density data, the excess partial molar volumes of glycerol V~E_(Gly) and from the thermal expansivity data, the normalized cross fluctuations ~SV#DELTA#, introduced by us earlier, were evaluated. While the detailed manner in which glycerol modifies the molecular arrangement of H_2O in its immediate vicinity is yet to be elucidated, the hydrogen bond probability in the bulk H_2O away from solute molecules is reduced gradually as the glycerol composition increases to the point where putative presence of icelike patches is no longer possible. Thereupon, a qualitatively different mixing scheme seems to set in.