<P> Solvation describes the interaction of solvent with molecules or ions in a solute . Ions, and to some cases, molecules, interact strongly with solvent, and the strength and nature of this interaction influences many properties of the solute, including solubility, reactivity, and color . In the process of solvation, ions are surrounded by concentric shells of solvent . Solvation is the process of reorganizing solvent and solute molecules into solvation complexes . Solvation involves bond formation, hydrogen bonding, and van der Waals forces . Solvation of a solute by water is called hydration . </P> <P> Solubility of compounds represents a competition between lattice energy and solvation as well as entropy effects related to changes in the solvent structure . </P> <P> By an IUPAC definition, solvation is an interaction of a solute with the solvent, which leads to stabilization of the solute species in the solution . In the solvated state, an ion in a solution is surrounded or complexed by solvent molecules . Solvated species can often be described by coordination number, and the complex stability constants . The concept of the solvation interaction can also be applied to an insoluble material, for example, solvation of functional groups on a surface of ion - exchange resin . </P> <P> Solvation is, in concept, distinct from solubility . Solvation or dissolution is a kinetic process and is quantified by its rate . Solubility quantifies the dynamic equilibrium state achieved when the rate of dissolution equals the rate of precipitation . The consideration of the units makes the distinction clearer . The typical unit for dissolution rate is mol / s . The units for solubility express a concentration: mass per volume (mg / mL), molarity (mol / L), etc . </P>

Which process cannot separate solute from solvent in a true solution