Saturated facts

A saturated solution contains the maximum amount of dissolved solute possible at a given temperature. If it has less than this amount, it’s called an unsaturated solution.

Sometimes, under unusual circumstances, the solvent may actually dissolve more than its maximum amount and become supersaturated. This supersaturated solution is unstable, though, and sooner or later, the solute will precipitate (form a solid) until the saturation point has been reached.

If a solution is unsaturated, then the amount of solute that’s dissolved may vary over a wide range. A couple of rather nebulous terms describe the relative amount of solute and solvent that you can use:

✓ Dilute: You can say that the solution is dilute, meaning that relatively speaking, there’s very little solute per given amount of solvent. If you dissolve 0.01 grams of sodium chloride in a liter of water, for example, the solution is dilute. (Another dilute solution? A $1 margarita, as one of my students once pointed out — that’s a lot of solvent [water] and very little solute [tequila].)

✓ Concentrated: A concentrated solution contains a large amount of solute per the given amount of solvent. If you dissolve 200 grams of sodium chloride in a liter of water, for example, the solution is concentrated.

But suppose you dissolve 25 grams or 50 grams of sodium chloride in a liter of water. Is the solution dilute or concentrated? These terms don’t hold up very well for most cases.