Perfect solutions thermodynamic properties

A continuum solvent replaces explicit atomic details with a bulk, mean-field response. It is possible to demonstrate from statistical mechanics that an implicit solvent potential of mean force (PMF) exists, which preserves exactly the solute thermodynamic properties obtained from explicit solvent. It is possible to formulate a perfect implicit solvent in principle, but in practice approximations are necessary to achieve efficiency. This remains an active area of research.An implicit solvent PMF can be formulated via a thermodynamic cycle that discharges the solute in vapor, grows the uncharged (apolar) solute into a solvent W pgi fX), and finally recharges the solute within a continuum dielectric Weiec(X)... 

This equation applies to those molecules in solution, regardless of the presence of other molecules, such as enzyme-boimd compounds. If DPNH is preferentially removed from the solution by combination with the enzyme, the reaction must proceed in the direction of DPNH formation to satisfy the equation. It is perfectly possible to calculate an equilibrium involving enzyme-bound DPN, but this is a property of a different system. Such an additional system cannot alter the thermodynamic properties of the system of free compounds. The preferential binding of DPNH pulls the reaction in the same manner as any other coupled reac-... 

The models used to deseribe the thermodynamic properties of solid solutions are the same as for liquid solutions. The h5rpotheses upon which these models are founded can be easily applied - all the more because the h q)othesis of the pseudo-lattice used for liquid solutions now becomes perfectly appropriate, and is no longer a hypothesis, but simply corresponds to the crystalline lattice. 

From (1.5.6) important thermodynamic properties of perfect solutions may be directly deduced e.g. Raoult s law for the vapour pressure, osmotic pressure, equilibrium between a liquid solution and a solid phase. 

From (4.3.10) we may deduce all thermodynamic properties of the mixture. Let us notice that F (F, T) is the free energy of the perfect solution for which fn = 1. This indudes the corresponding... 

These considerations and the existence of many solutions for whidi the excess functions g and have not the same sign indicate that presumably no theory limited to first order terms can at all give an adequate description of the thermodynamic properties of mixtmres. This may be taken as a consequence of the fact that the combining rule (2.7.8) seems to be a feiir ai roximation for mixtures of spherical nonpolar molecules. If the interaction i2 is somewhere between the arithmetical and geometrical mean of u and 22. i becomes a second order quantity (cf. 2.7.9) and the theory of conformal solutions would predict no deviations from the laws of perfect solutions. In order to force agreement using only first order terms, this approach has to overemphasize the deviations from the combining rules (2.7.8) or (2.7.10). This IS probably the reason of the discrepancy between (4.4.1) and (4,4.2). 

As it is perfectly known, room temperature molten salts or ionic liquids (ILs) are charged complex fluids formed exclusively by ions. They can be seen as an infinitely concentrated electrolyte solution, and one can think about these systems as the opvposite limit to that of the applicability of the DH theory of ions solutions. It is well-known that a polar network exists in these systems, as can be seen for example in (Wei Jiang et al., 2007), so, from the theoretical perspective, one expects that a pseudolattice model is particularly well adapted to the peculiarities of ILs. Indeed, Turmine and coworkers (Bou Malham et al., 2007 Bouguerra et al. 2008) proved that the so called Bahe-Varela (BV) pseudolattice theory of electrolyte solutions is capable of accoxmting for the thermodynamic properties of binary and ternary mixtures of ILs up to the limit of pure IL. 

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