By Pheori Wiley, Updated Mar 24, 2022
Salts are ionic solids, meaning their constituent ions are bound by strong electrostatic forces. Dissolving them requires breaking these bonds and separating the ions.
Water’s polarity index of 9 makes it the most effective solvent for ionic compounds. Each water molecule surrounds a cation or anion, stabilizing it through hydrogen bonding and electrostatic interactions, which keeps the ions apart in solution.
While water is the most common solvent, other high‑polarity liquids can also dissolve certain salts. Dimethyl sulfoxide (DMSO), with a polarity index of 7.2, is the next best alternative, followed by ethanol (5.2) and acetone (5.1). These solvents work best for salts that are moderately soluble in water or that form stronger hydrogen bonds with the solvent.
According to Purdue University, a salt is considered soluble if it can dissolve in room‑temperature water to at least 0.1 mol L⁻¹, and insoluble if the concentration does not exceed 0.001 mol L⁻¹. Common soluble salts include sodium chloride, nitrates, chlorides, and sulfates. Insoluble salts often contain sulfides, oxides, hydroxides, chromates, and phosphates.
For precise solubility data, consult the New World Encyclopedia or the Chemical‑Ecology.net database.
