= Solvation
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<Solvation> is stabilization through interactions between a <solute> and its <solvent>. It involves both the <solute>'s surroundings and reorganization of the <solvent>: neighbors move, orientations change, and existing interactions compete with new ones. <Electric forces>, <Van der Waals forces>, and specific interactions such as <hydrogen bonds> can contribute. <Solvation> can also occur at groups on an insoluble material, so it does not require complete <dissolution>.<IUPAC Compendium of Chemical Terminology (Gold Book) by International Union of Pure and Applied Chemistry/solvation>{ref}
<Solvation> by <water> is called hydration. <Hydration of ions> is the charged special case, but neutral <molecules> such as <sucrose> can also interact with <water> without becoming <ions>. A hydrated <cation> retains its positive net <electric charge>; orienting neutral <water> <molecules> around it does not supply an extra <Electron>. <Dissolution>, <desolvation>, and <ionization> describe different changes, as the examples below show.<Chemistry 2e by Paul Flowers and others/11.1 The Dissolution Process>[Opening sucrose example]{ref}<Chemistry 2e by Paul Flowers and others/11.2 Electrolytes>[“Ionic Electrolytes” and “Covalent Electrolytes”]{ref}
The useful question is therefore not just whether a <solute> attracts a <solvent>, but how much the whole system gains after paying for the rearrangements. <Solvation free energy> describes a specified transfer into a <solvent>; <solvation thermodynamic balance> explains why even cooling during <dissolution> can accompany favorable mixing. The existing <solubility> discussion concerns how much remains dissolved at <chemical equilibrium>.
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