A supersaturated solution is a solution that contains more dissolved solute than is normally possible at a given temperature. This means that the solution is holding onto solute particles that would normally precipitate out of the solution. Supersaturated solutions are metastable, which means that they are in a state of unstable equilibrium. A slight disturbance, such as a small change in temperature or the introduction of a foreign particle, can cause the solution to nucleate and the excess solute to precipitate out of the solution.
Supersaturated solutions are created by heating a saturated solution above its normal melting or boiling point. This allows the solvent to dissolve more solute than it normally could. When the solution is cooled back down to its normal temperature, the excess solute is still dissolved in the solution.
Here are some examples of supersaturated solutions:
- Supersaturated sugar solutions: These solutions can be made by heating a solution of sugar and water to a high temperature and then slowly cooling it down. The sugar will remain dissolved in the solution even though it is above its normal solubility limit.
- Supersaturated salt solutions: These solutions can be made by dissolving salt in water and then adding a small amount of alcohol. The alcohol will lower the solubility of the salt, causing the solution to become supersaturated.
- Supersaturated sodium thiosulfate solutions: These solutions are often used in science demonstrations because they can be easily made and triggered to precipitate by adding a small crystal of sodium thiosulfate.
Supersaturated solutions have a number of applications, including:
- Pharmaceuticals: Supersaturated solutions can be used to prepare drugs that are more stable and have a longer shelf life.
- Cosmetics: Supersaturated solutions can be used to improve the appearance of cosmetics, such as by making them more shiny or pearlescent.
- Food industry: Supersaturated solutions can be used to make certain foods, such as ice cream, more creamy and smooth.
Supersaturated solutions are a fascinating example of the behavior of matter. They are a testament to the delicate balance that exists between solutes, solvents, and temperature.