Solutions contain the maximum, less than the maximum, or more than the equilibrium amount of solute respectively.
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A saturated solution contains the maximum amount of solute that can dissolve at a given temperature and is in equilibrium with undissolved solute. An unsaturated solution contains less solute than this maximum and can dissolve more. A supersaturated solution contains more dissolved solute than equilibrium allows, so it is metastable and tends to crystallize rapidly when disturbed or seeded with a crystal. Supersaturation is commonly prepared by dissolving solute at high temperature and then cooling the solution slowly. Supersaturated sodium acetate solutions release heat when crystallization is triggered, as used in reusable hand warmers.
Key ideas: Test: add a crystal of solute. Saturated stays unchanged, unsaturated dissolves it, and supersaturated causes rapid crystallization. On a solubility curve, points below the curve are unsaturated, points on it saturated, and points above supersaturated. Crystallization by cooling uses the curve, with recovery equal to the difference in solubility.
Common mistakes and connections: Students think saturated means concentrated, but a saturated solution of a sparingly soluble salt can be very dilute. Another error is that supersaturated solutions are stable at equilibrium. They are metastable and need a nucleation site. Cooling can give a supersaturated solution only when done slowly and cleanly. Links to solubility curves, crystallization and Ksp.
Saturated, unsaturated and supersaturated solutions differ in dissolved amount relative to the solubility limit; a seed crystal can trigger crystallization. The interactive lesson shows this as a live animation or chart.
Rock candy forms as crystals grow slowly from a supersaturated sugar syrup.
Solutions contain the maximum, less than the maximum, or more than the equilibrium amount of solute respectively.
Saturated Unsaturated Supersaturated is a beginner topic in States of Matter & Solutions. It needs no earlier chemistry lessons and is a good starting point.
Study these earlier topics in States of Matter & Solutions first: Solution, Solute and Solvent, Solubility.
The next topics in States of Matter & Solutions are Like Dissolves Like and Molarity.
Yes. The interactive lesson includes a self-check question on Saturated Unsaturated Supersaturated, and the States of Matter & Solutions quiz draws on every topic in this area.
Saturated Unsaturated Supersaturated is topic 74 of 109 in States of Matter & Solutions.