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Two substances are said to be miscible when they can be completely mixed to give a homogeneous solution . This term is commonly used to describe the mixture of liquids, but it can also be applied to gases and solids.
In addition to being completely mixed, the two substances must do so in all proportions and in all concentrations, that is, it does not matter if there is a greater proportion of one compound than of the other, or vice versa, that the mixture must be given completely.
Examples of homogeneous mixtures
Ethanol and water are two miscible liquids. Regardless of the ratio in which they are mixed, they form a solution. Benzene in acetone is miscible, as is the case with the organic compounds of hexane and xylene.
All gases are miscible with each other at normal pressures. For example, helium and nitrogen, when in a gaseous state , are miscible. With ethanol and water in vapor form, the same thing happens, they are miscible.
The miscibility between solids is observed in a different way, since it is formed from molten liquids that later solidify. The elements that form alloys are miscible, as is the case with iron and carbon, forming steel. Copper and zinc are also miscible, giving rise to brass.
How is miscibility identified?
You can conclude that two liquids are miscible simply by looking at them. Mixing two miscible liquids produces a clear result, while two immiscible liquids show a cloudy mixture. However, if the two liquids have the same color and similar refractive indices, it is difficult to distinguish the possible layers that can form when two immiscible liquids are brought together.
In the case of solids , when they are completely miscible, after mixing the molten solids and their subsequent solidification, a homogeneous solid will be obtained. By the time you separate them, they separate completely.
Factors Determining Miscibility
Among the factors that determine miscibility, it seems that polarity is among them. For this reason, organic compounds that share the same polarity are usually miscible with each other. In the same way that it is also said that “like dissolves like”, hence polar solvents can mix with other polar solvents, while nonpolar solvents will mix with nonpolar solvents.
Sources
- Helmenstine, A. (2020). Miscible Definition in Chemistry – What Is Miscibility?. Retrieved 19 April 2021, from https://sciencenotes.org/miscible-definition-in-chemistry-what-is-miscibility/
