The solubility of sodium chloride, table salt, is 36 grams per 100
grams of water at 20^{o}C.
When we place 40 grams of table salt in 100 grams of water at 20^{o}C,
36 grams will become dissolved in water. The remaining undissolved
crystal will remain as a solid in the solution. This is a saturated
solution. However, solubility increases with temperature. This
means that at higher temperature, the solubility of table salt is
greater than 36 grams in 100 grams.
If we increase the temperature to 30^{o}C, the remaining
4 grams of undissolved table salt crystal will dissolve into the solution.
At 30^{o}C, this solution contains less solute than the solubility
limit. Therefore, at 30^{o}C, this solution becomes unsaturated.
