Dhc. Chen et al., Excess chemical potentials, partial molar enthalpies and entropies in binary aqueous acetone and tetramethyl urea at 25 degrees C, FLU PH EQUI, 175(1-2), 2000, pp. 35-43
We measured excess chemical potentials, mu (E)(i), excess partial molar ent
halpy, H-i(E), of solute i in aqueous acetone and tetramethyl urea (TMU). W
e then evaluated excess partial molar entropy, S-i(E). They all were determ
ined accurately and in small increments in mole fraction, and hence, it was
possible to take one more derivative with respect to mole fraction. These
higher derivatives were used to learn more about intermolecular interaction
in solution. Furthermore, they were used to detect anomalous thermodynamic
behaviour, in particular a qualitative change in mixing scheme. We conclud
e that in both aqueous solutions, three distinctively different mixing sche
mes are operative depending on the composition range, and that in the most
H2O-rich region, solute molecules enhance the hydrogen bond network of H2O
in their immediate vicinity. However, the hydrogen bond probability in the
bulk of H2O away from solute is reduced. (C) 2000 Elsevier Science B.V. All
rights reserved.