What is the term used for such a solution that contains more dissolved solute than is normal?

In order to continue enjoying our site, we ask that you confirm your identity as a human. Thank you very much for your cooperation.

Índice Show

Recommended Videos
Supersaturation in Phase Change (Crystallization and Condensation)
Applications of Supersaturated Solution
Examples of Supersaturated Solution
Solved Examples

A solution is a homogeneous mixture of two or more pure substances on molecular level whose composition can vary within certain limits. A solution has two components (substances) known as solute and the solvent.

A supersaturated solution contains more dissolved solute than required for preparing a saturated solution and can be prepared by heating a saturated solution, adding more solute, and then cooling it gently. Excess dissolved solute crystallizes by seeding supersaturated solution with a few crystals of the solute.

Supersaturation in Phase Change (Crystallization and Condensation)

Physical processes and chemical processes in the vapour melt or solution phase of every system take place through the formation of three-dimensional 3D nuclei of a new phase and occur only when the medium is supersaturated.
The formation of the nuclei is associated with a change in the free energy of the system. In the homogeneous system nuclei of the new phase are not formed as soon as the system becomes supersaturated even though thermodynamically such a situation is possible.
The system is said to be in a state of metastable equilibrium and it can remain in that state without attaining the minimum free energy corresponding to the equilibrium state.
In other words, in such cases nucleation of the new phase sets in after some period the value depends on such factors as the temperature and pressure of the system, the presence of chemical phases different from the nucleating phase and increased supersaturation level facilitate the process of nucleation of the new phase.
However, there is always a supersaturation level when the new phase nucleates instantaneously. That is the new phase precipitates.
This supersaturation level corresponds to the upper limit of the state of metastable equilibrium and defines the width of the metastable width.

Applications of Supersaturated Solution

When a solution of a solid solute dissolved in a liquid solvent is saturated, it is in thermodynamic equilibrium. In order for crystallization to occur, the state of the system must be shifted to a nonequilibrium state in which the concentration of the solute in the solution exceeds its equilibrium concentration at the given solution conditions. Solutions that are in the nonequilibrium state are said to be supersaturated. The simplest method to create a supersaturated solution is by cooling.

A solution is initially prepared at point A. If this solution is cooled it will be saturated when it intersects the saturation line. If it is cooled past the saturation line to point B it will be supersaturated. Just because this solution is supersaturated, however, does not mean that it will immediately crystallize. Supersaturated solutions are metastable. This means that there is a free energy barrier which must be overcome for the phase transition to be overcome.

The simplest and most common method of making a supersaturated solution is by cooling, but this is not the only method that can be used, there are many methods like solvent evaporation, temperature change, change in pH, chemical reaction and alteration in solvent composition.

Examples of Supersaturated Solution

Supersaturated solution contains more dissolved substances than a saturated solution. For example, 40g NaCl in 100ml H2O. The additional 4.0g NaCl remains undissolved.

Solved Examples

1. What is the mass percent of sodium hydroxide in a solution that is made by dissolving 8.00g NaOH in 50.0g H2O?

Solution:

Knowns 8.00g NaOH

50.0g H2O

Solving for mass percent

= 8.00g NaOH/8.00g NaOH + 50.0g H2O

= 13.8% NaOH solution.

2. Will a solution made by adding 2.5g of CuSO4 to 10g of H2O be saturated for unsaturated at 20oC?

Solution:

We first need to know the solution of CuSO4 at 20oC. From figure 14.4 we see that the solubility of CuSO4 at 20oC is about 21g per 100g of H2O. This amount is equivalent to 2.1g of CuSO4 per 10g of H2O.

Since 2.5g per 10g of H2O is greater than 2.1g per 10g of H2O, the solution will be saturated and 0.4g of CuSO4 will be maintained.

A supersaturated solution is a more solute solution than can be dissolved by the solvent. If you haven’t learned what a solute / solvent is, the material that is dissolved in the solution, such as salts but not restricted to salts, is a solution. The most popular example is sodium acetate which is supersaturated.

A supersaturated solution is a solution that contains more than the average solvent that can be dissolved at a given temperature. The recrystallization of the excess dissolved solvent in a super-saturated solution can be started by inserting a tiny solute crystal, called a seed crystal.

According to the solubility of the substance a “supersaturated” solution produces more dissolved content than it should. In the case of sugar, whose chemical name is “sucrose,” approximately 211 grams of water can dissolve in 100 millilitres. Solubility is temperature dependent; more sugar dissolves in hot water than in cold.

Under appropriate conditions, solutions may often be formulated that contain a greater amount of solvent than the one required to form a saturated solution. Owing to the presence of the solute in a supersaturated solution in a concentration greater than the concentration of equilibrium, super-saturated solutions are unstable.

The solid crystals in the hydrated crystals will dissolve into the bath, forming a supersaturated solution. When the solution for sodium thiosulfate is gradually cooled the super-saturated solution should remain liquid. Placing a small crystal in the over-saturated solution would make the liquid solid.

Put your understanding of this concept to test by answering a few MCQs. Click ‘Start Quiz’ to begin!

Select the correct answer and click on the “Finish” button
Check your score and answers at the end of the quiz

Visit BYJU’S for all Chemistry related queries and study materials

0 out of 0 arewrong

0 out of 0 are correct

0 out of 0 are Unattempted

View Quiz Answers and Analysis

A saturated solution is a chemical solution containing the maximum concentration of a solute dissolved in the solvent. The additional solute will not dissolve in a saturated solution.

The amount of solute that can be dissolved in a solvent to form a saturated solution depends on a variety of factors. The most important factors are:

Temperature: Solubility increases with temperature. For example, you can dissolve much more salt in hot water than in cold water.
Pressure: Increasing pressure can force more solute into solution. This is commonly used to dissolve gases into liquids.
Chemical Composition: The nature of the solute and solvent and the presence of other chemicals in a solution affects solubility. For example, you can dissolve much more sugar in water than salt in water. Ethanol and water are completely soluble in each other.

Jose Carlos Barbosa / EyeEm / Getty Images

You encounter saturated solutions in daily life, not just in a chemistry lab. Also, the solvent does not need to be water. Here are some common examples:

A soda is a saturated solution of carbon dioxide in water. This is why, when the pressure is released, carbon dioxide gas forms bubbles.
Adding chocolate powder to milk so that it stops dissolving forms a saturated solution.
Salt can be added to melted butter or oil to the point where the salt grains stop dissolving, forming a saturated solution.
If you add enough sugar to your coffee or tea, you can form a saturated solution. You'll know you've reached the saturation point when the sugar stops dissolving. Hot tea or coffee allows much more sugar to be dissolved than you can add to a cold beverage.
Sugar can be added to vinegar to form a saturated solution.

If one substance will not dissolve into another, you cannot form a saturated solution. For example, when you mix salt and pepper, neither dissolves in the other. All you get is a mixture. Mixing oil and water together will not form a saturated solution because one liquid does not dissolve in the other.

There's more than one way to make a saturated solution. You can prepare it from scratch, saturate an unsaturated solution, or force a supersaturated solution to lose some solute.

Add solute to a liquid until no more dissolves.
Evaporate solvent from a solution until it becomes saturated. Once the solution starts to crystallize or precipitate, the solution is saturated.
Add a seed crystal to a supersaturated solution so extra solute will grow onto the crystal, leaving a saturated solution.

The definition of a supersaturated solution is one which contains more dissolved solute than could ordinarily dissolve into the solvent. A minor disturbance of the solution or introduction of a "seed" or tiny crystal of solute will force crystallization of excess solute. One way supersaturation can occur is by carefully cooling a saturated solution. If there is no nucleation point for crystal formation, the excess solute may remain in solution.