Solution

In oxygen in water. Liquids may dissolve in other liquids. Gases can combine with other gases to form mixtures, rather than solutions.^[1] Solutions are characterized by interactions between the solvent phase and solute molecules or ions that result in a net decrease in free energy. Under such a definition, gases typically cannot function as solvents, since in the gas phase interactions between molecules are minimal due to the large distances between the moieties. This lack of interaction is the reason that gases can expand freely and the presence of these interactions is the reason that liquids do not expand.

Examples of solid solutions are concentration. Examples include molarity, molality, and parts per million (ppm).

Solutions should be distinguished from non-homogeneous mixtures such as suspensions.

Types of solutions

Many types of solutions exist, as gases can be both solvent and solute, in any combination:

Examples of solutions		Solute
Examples of solutions		Gas	Liquid	Solid
Solvent	Gas	nitrogen (air)
	Liquid	effervescence; the dissolved gas itself is not visible in the solution)	hydrocarbons in each other (petroleum)	amalgam
	Solid	platinum has been studied as a storage medium.	Hexane in paraffin wax, mercury in gold.	alloys

Solvents

Main article: Solvent

Liquid solvents can be broadly classified into emulsifiers, as they have the ability to stabilize emulsions by aligning themselves on the interface between the non-polar and polar liquids, with their polar ends in the polar liquid and their non-polar ends in the non-polar liquid.

Solvation

Main article: Solvation

During solvation, especially when the solvent is polar, a structure forms around it, which allows the solute-solvent interaction to remain stable.

When no more of a solute can be dissolved into a solvent, the solution is said to be solute, and then lowering it (for example by cooling).

Usually, the greater the temperature of the solvent, the more of a given solid solute it can dissolve. However, most gases and some compounds exhibit solubility that deacrease with increased temperature. Such behavior is a result of an surfactants exhibit this behaviour. The solubility of liquids in liquids is generally less temperature-sensitive than that of solids or gases.

Ideal solutions

Main article: ideal solution

The properties of an ideal solution can be calculated by the linear combination of the properties of its components.

If both solute and solvent exist in equal quantities (such as in a 50% ethanol, 50% water solution), the concepts of "solute" and "solvent" become less relevant, but the substance that is more often used as a solvent is normally designated as the solvent (in this example, water).

References

IUPAC Gold Book Definition

^ Streitwieser, Andrew; Heathcock, Clayton H., Kosower, Edward M. (1992²). Introduction to Organic Chemistry, 4th ed., Macmillan Publishing Company, New York. ISBN 0-02-418170-6.

v • d • e Articles related to solutions
Solution	Amphiphile

Categories: Colloidal chemistry

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