Thermodynamic Quantities of Solvation from Experimental Data

Calculation of the Thermodynamic Quantities of Solvation from Experimental Data 

Having defined the solvation process in the preceding section, we now turn to the question of evaluating the pertinent thermodynamic quantities from experimental data. We discuss in this section the case of a solvaton s which does not undergo dissociation 

Consider two phases a and P in which s molecules are distributed. We do not impose any restrictions on the concentration of s in the two phases. The only assumption being made is the applicability of classical statistical mechanics. At equilibrium, assuming that the two phases are at the same temperature and pressure, we have the following equation for the chemical potential of s in the two phases  

In the traditional thermodynamic treatment one usually imposes the restriction of a very dilute solution of s in the two phases. However, here we shall use the general expression (6.13.1) for the chemical potential of s in the two phases. Applying Eq. (6.13.1) to Eq. (6.13.12), we obtain 

Here p and Ps are the number densities of s in the two phases, at equilibrium. Relation (6.13.14) provides a very simple way of computing the difference in the solvation Gibbs energies of s in the two phases a and P from the measurement of the two densities and pf at equilibrium. The most useful particular example of (6.13.14) occurs when one of the phases, say a, is an ideal gas. In such a case = 0 and relation (6.13.14) 

---

Extracting the thermodynamic quantities of solvation from experimental data... 

Using standard thermodynamic relationships, we can derive all the thermodynamic quantities of solvation from experimental data using equation (7.31). 

---