Supersaturated Solution - Definition, Examples, Applications, FAQs

What is a Solution?

Before we begin with the supersaturated solution, let us first have a look at ‘what is a solution?’. In chemistry, two or more substances are homogeneously combined to form a solution. Those substances that get dissolved are referred to as solute and those substances in which solute is dissolved is solvent. For example, salt (solute) dissolved in water (solvent). The concentration of the solution is determined on the basis of the amount of solute dissolved in the solvent.

There is often a limit for the amount of solute that can be dissolved in a definite quantity of solvent. Especially, in cases where solids are dissolved in liquids. Based on the amount of solute that is dissolved in the solvent, solutions can be further classified as: saturated solution, unsaturated solution and supersaturated solution.

To understand these classification let us consider an example. If 36 g KCl is dissolved in 100 g of H₂O at room temperature, then only 35.5 g of KCl gets dissolved in it. The remaining KCl can be dissolved by raising the temperature somewhat, but on cooling to room temperature again, 0.5 g KCl will get precipitated, leaving exactly 35.5 g KCl in H₂O. Thus, we can say that, at room temperature, the solubility of KCl is 35.5 g per 100 g of H₂O. A solution of such composition can be described as a saturated solution since it can dissolve no more amount of KCl. Saturated meaning in urdu is seshuda.

Therefore, a saturated solution can be defined as the solution containing the utmost amount of solute that is able to dissolve in solvent at a particular given temperature.

Illustrating the same example of KCl given above, let us understand the phenomenon of unsaturation. Consider, if only 30 g of KCl is dissolved in 100 g of H₂O, then the addition of further amounts of KCl undergoes dissolving. This means that the solvent has the ability to dissolve more amounts of solute. A solution of such composition can be described as an unsaturated solution as it can dissolve more amount of KCl.

Thus, an unsaturated solution can be defined as the solution that is able to dissolve more amount of solute in a solvent at a particular given temperature. Unsaturated meaning in telugu is asantrapta.

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What is a Supersaturated Solution?

Supersaturation meaning or supersaturated solution meaning is, in some cases, it is possible to prepare a solution which behaves unusual and contains more amount of solute than present in a saturated solution. Such a solution is referred to as a supersaturated solution or super solution.

A supersaturated solution definition or supersaturated solution definition chemistry is that as the solution containing more than the maximum amount of solute that is able to dissolve in solvent at a particular given temperature. A supersaturated solution possesses an unstable state; it could be made stable by separating the excess amount of solute dissolved in the solvent.

Examples of Supersaturated solution

Examples of supersaturated solutions include carbonated water (i.e. soda water), honey or sugar syrup used in confectionery, etc.

An example of supersaturation is shown by sodium thiosulfate (Na₂S₂O₃). It can dissolve 50 g Na₂S₂O₃ per 100 g of H₂O at room temperature. Suppose, 70 g of Na₂S₂O₃ crystal is dissolved in 100 g hot H₂O and the solution is then cooled to room temperature. Then the additional 20 g of Na₂S₂O₃ usually does not get precipitated.

The solution thus obtained is a supersaturated solution and it is unstable. The recrystallization in a supersaturated solution can be performed by the addition of a small crystal of solute which is called a seed crystal. This process is define seeding in chemistry.

The nucleation site is provided by the seed crystal on which the extra dissolved crystals can begin to grow. The supersaturated solution of Na₂S₂O₃ can be seeded by the addition of a Na₂S₂O₃ crystal, in which the excess salt suddenly crystallizes and heat is liberated. After the crystals are settled and the temperature has cooled back to room temperature (25°C), the solution found above the crystal is a saturated solution and it contains 50 g Na₂S₂O₃. Recrystallization is a very fast process from a supersaturated solution.

Supersaturation in Phase Change (Supersaturation Crystallization and Condensation)

• In each system, the physical and chemical processes of the vapour melt or the solution phase occurs by the formation of a three dimensional nuclei of a new phase and takes place only during the supersaturated medium.
• The nuclei’s production is associated with a change in the free energy of the system. In the case of a homogeneous system, the new phase of the nuclei are not produced as soon as the system becomes supersaturated though thermodynamically, such a situation becomes possible.
• The system is found to be in a metastable equilibrium state, and it can remain in the same state without attaining the least or minimum free energy corresponding to the equilibrium state.
• In other words, in such cases, the nucleation of new phase sets in after a time period, where the value depends on factors such as the pressure and temperature of the system, the presence of chemical phases varies from the increasing supersaturation level, and nucleating phase facilitates the nucleation process of the new phase.
• However, there is always a level of supersaturation when the new phase is instantaneously nucleated. It is referred to as the new phase precipitates.
• Such a supersaturation level signifies the upper limit of the metastable equilibrium state and describes the metastable width.

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Applications of Supersaturated Solution

• Supersaturation have practical applications in field of pharmaceuticals. By preparing a supersaturated solution of a particular drug, it can be ingested in liquid form. The precipitation can be prevented by adding precipitation inhibitors. Drugs in such states are termed as "supersaturating drug delivery services," or "SDDS." Oral consumption of a drug in this form is easy and helps in the measurement of very precise dosages.
• The marine ecologists use supersaturated solutions’ identification as a tool for the study of activity of organisms and populations.
• Supersaturation is an important factor in the design of steam turbines.
• The study of supersaturation is also important for atmospheric studies. Actually, supersaturation of water is very common in the upper troposphere. This can be found using satellite data from the Atmospheric Infrared Sounder.

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