Excess chemical potentials, excess partial molar enthalpies, entropies, volumes, and isobaric thermal expansivities of aqueous glycerol at 25°C

The vapor pressures p the excess partial molar enthalpies of glycerol He,, the densities d and the thermal expansivities oc, of aqueous glycerol were measured at 25 degrees C. From the vapor pressure data, the excess chemical potential of H2O mu(W)(E) was calculated, assuming that the partial pressure of glycerol Poly is negligibly small. The excess chemical potential of glycerol mu(Gly)(E) was estimated by applying the Gibbs-Duhem relation and these data were used to calculate the excess partial molar entropies S-Gly(E). From the density data, the excess partial molar volumes of glycerol V-Gly(E) 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 H2O in its immediate vicinity is yet to be elucidated, the hydrogen bond probability in the bulk H2O 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.