Solvation Thermodynamics and Its Applications

Abstract

In this article, we start by describing a few "definitions" of the solvation processes, which were used in the literature until about 1980. Then, we choose one of these definitions and show that it has a simple molecular interpretation. This fact led to a new definition of the solvation process and the corresponding thermodynamic quantities. The new measure of the solvation Gibbs energy has a simple interpretation. In addition, the thermodynamic quantities associated with the new solvation process have several other advantages over the older measures. These will be discussed briefly in the third section. In the fourth section, we discuss a few applications of the new solvation process.

Keywords: Gibbs energy of solvation; solvation; thermodynamics.

Figure 1

The process of adding a new particle α (black particle) into the system (of black and white particles) is split into two steps: first, the particle is placed at a fixed position, then it is released. The corresponding changes in Gibbs energies are the pseudo CP and the liberation Gibbs energy.

Figure 2

Definition of the solvation process: a molecule α is transferred from a fixed position in an ideal gas phase to a fixed position in a liquid phase.

Figure 3

The process of bringing the two solute particles (S) from infinite separation $\left({\mathit{R}}_{12}=\infty \right)$ to some finite distance ${(\mathit{R}}_{12}=\mathit{R}).$ The process is carried out in an ideal gas and in a liquid phase.

Figure 4

The process of transferring a methyl group from position 4 to position 2, relative to a methyl group at position 1.