Unsaturated Solutions

An unsaturated solution is a chemical solution in which the concentration of the solute is lower than the solubility of its equilibrium. If the amount of dissolved solute is equal to the saturation point of the solvent, the solution is called a saturated solution.

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Saturation and Solubility

Solubility is the measure of the volume of solute that can dissolve in a solvent. Solubility is dependent on the solvent. Salt dissolves in water, for instance, but not in oil. With an increase in temperature, the solubility of solids in water typically increases. In hot water, for example, you can dissolve more sugar or salt than in cold water. Solubility often depends on pressure, but it is less of a determining factor, and in daily calculations, it is mostly ignored. Since solubility depends on temperature, an unsaturated solution at higher temperatures can become saturated or even supersaturated at lower temperatures. Scientists and cooks commonly use heat to prepare unsaturated solutions when the solute does not dissolve entirely at a lower temperature. 

Types of Saturation

There are three levels of saturation in a solution.

1. There is less solute in an unsaturated solution than the amount of solute it can dissolve. There is no unsolved matter left of the solute in such solutions. 

2. A saturated solution contains more solvent per volume than an unsaturated solution. The solute has dissolved until it could not be dissolved anymore, leaving some undissolved matter in the solution. Usually, the undissolved substance is denser than the solution and sinks to the bottom of the container.

3. There is more solvent dissolved in a supersaturated solution than in a saturated solution. The solvent will easily be separated from the solution through crystallization or precipitation. Special conditions may be required to supersaturate the solution. It helps to heat a solution to increase solubility so that more solute can be added. 

Properties of Unsaturated Solutions

• Unsaturated solutions are typically highly reactive than saturated solutions. For example, with a high amount of unsaturated fatty acids, linseed oil, triglyceride olive oil is more rapidly deposited than those with a high amount of saturated fatty acid deposits such as coconut fat.

• In a long carbon chain, a fatty acid with a double or triple bond can cause a curve in the carbon chain.

• Some hydrocarbons prevent the rotation of the atoms about the bond by locking them into specific structural formations.  

Examples of Unsaturated Solutions

• Adding a spoonful of sugar to a hot cup of coffee produces an unsaturated sugar solution. 

• Vinegar is an unsaturated acetic acid solution in water. 

• Mist is an unsaturated water vapor solution in the air. 

• As the solvent, gaseous solutions have gas, and the solute can either be in a solid, liquid, or even gaseous state. Good examples of unsaturated gaseous solutions include air, smoke, and mist.

• 0.01 M HCl is an unsaturated hydrochloric acid solution in water.

The concentration of solute in an unsaturated solution is much lower than its solubility equilibrium. For a particular solvent, each solution will have a limit. Therefore, for solubility in the solvent, solutes show a specific value.

Factors Affecting Saturation

• As temperature increases, the solubility of ionic solutions increases with the formation of anion-containing compounds. 

• The solids must be finely divided to have greater solubility. 

• Concentration builds at the solvent surface, causing higher crystallization in a still solution, so stirring the solution prevents the build-up by maximizing the net dissolving rate.

• The rate of crystallization will depend on the concentration of the solute at the crystal surface, depending mainly on the temperature, as opposed to the rate of solubility. 

• The solution would be saturated and if the solubility and crystallization rates are the same, dynamic equilibrium can be achieved. 

Facts

• More solute can be dissolved in the unsaturated solution before it reaches its saturation point. When the solution reaches the point of saturation, no more solute is dissolved in the solvent, and this solution is considered a saturated solution. Both solutions are thus initially unsaturated in nature, and ultimately, by applying a solution to it, it is transformed into a saturated solution.

• A solute is called a component of a solution dissolved in a solvent and present in a smaller quantity in a solution. The solvent is called the part of a solution that is present in a greater amount and dissolves the solution in it. For example, in a solution containing sugar and water, sugar acts as a solute, and water acts as a solvent, and the solution containing water is called an aqueous solution.

More about Unsaturated Solutions

A chemical solution in which the concentration of the solute is lower than the solubility of its equilibrium is what an unsaturated solution is. If the amount of dissolved solute is equal to the saturation point of the solvent, the solution is called a saturated solution. With respect to any specific solvent, each individual solute has its own limits.

When we add a solute to a solvent for the formation of a solution, initially the solute dissolves in a solvent and makes a uniform solution, and such types of solution where the solutes dissolve are called unsaturated solutions.  As we know, a solution comprises two different types of particles, solutes, and the solvent, and in a majority of cases, water is used as a solvent (which is a reason why water is known as the universal solvent).

These solutions that are unsaturated have the ability to dissolve solutes in them until they reach the saturation point. Once they reach their saturation point, the solutes will not get dissolved in the solvent. These are known as unsaturated solutions. Therefore, we can say that almost all solutions are unsaturated in nature and they get converted to a saturated solution by adding solute with them.

Examples of Unsaturated Solutions 

If the quantity of dissolved salt/sugar is below the saturation point,  then the sugar, as well as the salt dissolved in water, is an unsaturated solution.

Another example is Iced Coffee. Here each solute possesses a  different solubility rule and the solutes all dissolve into the solvent.  Those solutions are considered to be unsaturated solutions. Tea and sugar solution is another example of an unsaturated solution because they dissolve more amount of sugar in them. 

Once these types of solutions reach their saturation point, they get converted to what is known as Saturated Solutions.

The various Gaseous solutions have a gas that acts as a  solvent and the solute can be in a solid-state, liquid state, or even in a gaseous state. Some popular examples of unsaturated gaseous solutions are smoke and mist.

Properties of Unsaturated Solutions

1. The Unsaturated solutions are highly reactive than the saturated solutions.  For example, with high linseed oil, triglyceride olive oil, which has high amounts of unsaturated fatty acids, gets deposited slowly compared to those that have a high amount of saturated fatty acid deposits. An example of this is coconut fat.

2. A fatty acid with a double or triple bond can cause a curve in the carbon chain, in the case of a long carbon chain. 

3. Rotation of the atoms about the bond are prevented by certain hydrocarbons,  by locking them into specific structural formations.