Typically, the amount of solute that can be dissolved in a given amount of solvent at a given temperature is limited. When this limit is reached, we have a saturated solution, and any additional solute simply settles to the bottom of the solution.
A saturated solution is one in which no more solute can be dissolved in a specific amount of solvent at a given temperature.
Its solubility better explains the extent of a solute's dissolution in a solvent. Solubility measures how much of a solute can be dissolved in a given amount of a solvent.
Solubility is defined as the number of grams of a solute that can be dissolved in \(100 g\) of a solvent to form its saturated solution at a given temperature and pressure.
To form a saturated solution at \(25°C\), \(36 g\) of sodium chloride must be dissolved in \(100 g\) of water. Thus, at \(25°C\), the solubility of \(NaCl\) in water is \(36 g\).
The solubility is expressed mathematically as
\(\text{Solubility}\) \(=\) \(\frac{\text{Mass of the solute}} {\text{Mass of the solvent}}\) \(\times 100\)
Let us see some of the solubility range of common substances in water at \(25°C\):
Name of the solute
Formula of the solute
Solubility \(g/100g\) water
Calcium carbonate
\(CaCO_3\) (s)
Sodium chloride
\(NaCl\) (s)
\(NH_3\) (g)
Sodium hydroxide
Sodium bromide
Sodium iodide
Recall: Solubility refers to the maximum amount of a substance dissolved in a given volume of solvent. Solubility in water is frequently expressed in gram/\(100\)mL.
An unsaturated solution is one that has not reached its maximum solubility. This means that more solute could be added to the solvent, and dissolving would continue.
A solution that has attained maximum solubility is called a saturated solution.
Supersaturated solutions are those in which the dissolved solute has risen above the normal saturation point. Typically, a condition such as increased temperature or pressure is required to produce a supersaturated solution.