Partial molal entropy of mixing

Either of these expressions could be substituted for the ideal partial molal entropy of mixing, as deLned in Equation 2.2. The Flory-Huggins approach, for example, has been used to improve the prediction of the solubility of sulfamethoxypyridazine (Bustamante et al., 1989) and temazepam (Richardson et al., 1992) in a wide variety of solvents, including water. 

Substituting Equation 2.35 for the partial molal enthalpy of mixing, along with Equation 2.2 for the partial molal entropy of mixing, which is still considered ideal, and Equation 2.10 for the free energy change in Equation 2.6, gives... 

Cantor and SchimmeP provide a lucid description of the thermodynamics of the hydrophobic effect, and they stress the importance of considering both the unitary and cratic contributions to the partial molal entropy of solute-solvent interactions. Briefly, the partial molal entropy (5a) is the sum of the unitary contribution (5a ) which takes into account the characteristics of solute A and its interactions with water) and the cratic term (-R In Ca, where R is the universal gas constant and ( a is the mole fraction of component A) which is a statistical term resulting from the mixing of component A with solvent molecules. The unitary change in entropy 5a ... 

The partial molal entropy of component i is given by The entropy of mixing of the ideal mixture is... 

In the event that the molar volumes of solute and solvent are not comparable, and the thermal agitation is not adequate to achieve maximum entropy of mixing, a nonideal entropy of mixing exists (Bustamante et al., 1989). Two equations that account for the nonideal entropy of mixing have been derived by considering the partial molal volurfiA,and the volume fraction, occupied by each solution component. The L rst was developed by Flory and Huggins (Hildebrand, 1949 Kertes, 1965) ... 

Partial molal free energies, enthalpies and entropies were calculated from the activity data. The integral free energy, enthalpy and entropy of mixing were... 

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