What is Solvation Free Energy (SFE) ?
For solvation to occur, energy is required to release individual ions and molecules from the crystal lattices in which they are present. This is necessary to break the attractions the ions have with each other and is equal to the solid’s lattice free energy (the energy released at the formation of the lattice as the ions bonded with each other).
The energy for this comes from the energy released when ions of the lattice associate with molecules of the solvent. Energy released in this form is called the free energy of solvation.