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Desolvation removes some or all of the solvent environment of a species. Removing a hydration shell does not remove an ion's electric charge. Complete reversal of a specified solvation transfer reverses its Gibbs free energy and enthalpy changes when the same states and conventions are used. Partial desolvation, exchange of one solvent for another, and creation of a gaseous species have different endpoints; their costs need not match.

The functional group interaction profile compares donor strength $\alpha$ and acceptor strength $\beta$. In water, strong–strong contacts compensate for desolvation, giving the upper-right black region. Strong–weak contacts lose favourable solvent interactions without adequate replacement, giving the two grey regions. Weak–weak association gives the lower-left black region through the hydrophobic effect.

Ethanol's ethyl groups preferentially solvate weakly polar sites, removing this incentive for their association: the lower-left region becomes approximately neutral. Its hydroxyl group retains competition for hydrogen bonds elsewhere in the profile.^[ref]

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.^[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.^[ref][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.