A homogeneous mixture is a solid, liquid, or gaseous mixture that has a uniform composition. No matter where you sample the mixture, the amount and type of components is the same. In contrast, a heterogeneous mixture lacks a uniform composition, so samples won’t be identical.
Properties of Homogeneous Mixtures
Homogeneous mixture display certain properties:
- A homogenous mixture consists of a single phase. It consists only of a solid, liquid, or gas.
- While the components of the mixture retain their chemical identity, they aren’t visibly separate. But, at the molecular level, the mixture contains multiple compounds or elements.
- Samples taken from different parts of the mixture have identical composition and characteristics.
- It’s usually not possible to separate components of a homogeneous mixture using a mechanical method like filtration.
10 Homogeneous Mixture Examples
Here are ten examples of homogeneous mixtures:
- Sea water
- Natural gas
- Nitrox, heliox, or trimix (breathing mixtures for diving)
Any chemical solution or alloy is a homogeneous mixture. Examples of solutions include sugar water and powdered drink mix in water, while alloys include sterling silver and bronze. Emulsions are homogeneous mixtures, although they often become heterogeneous when examined microscopically. Examples of emulsions are homogenized milk, mayonnaise, and egg yolk.
Homogeneous Mixture vs Pure Substance
It may be impossible to visually distinguish between a homogeneous mixture and a pure substance. However, you can tell them apart if you know their composition. There is more than one component in a homogeneous mixture, while a pure substance consists of a single element or compound. Iron is a pure substance, while steel is a homogeneous mixture. Oxygen gas (O2) is a pure substance, while air is a homogeneous mixture. Water (H2O) is a compound, but sea water is a homogeneous mixture.
A compound forms when elements and molecules chemically react with each other to make new products. Constituents of a homogeneous mixture do not react with each other and do not form new products.
How to Tell Homogeneous and Heterogeneous Mixtures Apart
Two ways to distinguish between homogeneous and heterogeneous mixtures are by visual inspection and chemical analysis. If you can see individual components in a mixture, it’s heterogeneous. If you analyze two samples from a mixture and they aren’t the same, it’s heterogeneous. Similarly, if a mixture has a uniform appearance and the composition of different samples is the same, it’s homogeneous.
Remember, “heterogeneous” and “homogeneous” are a matter of scale. Even a homogeneous mixture becomes heterogeneous if the sample size is small enough. For example, blood is a homogeneous mixture, but it appears heterogeneous under magnification.
Homogenization is a process that turns a heterogeneous mixture into a homogeneous mixture. The term is applied to liquid mixtures. Homogenized milk is a good example. Ordinarily, milk separates into layers over time. Homogenization breaks up the fat globules in milk (the cream) to evenly disperse them, forming an emulsion. Homogenized milk maintains its uniform composition, so it is a homogeneous mixture.
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- IUPAC (1997). “Mixture.” Compendium of Chemical Terminology (the “Gold Book”) (2nd ed.). Oxford: Blackwell Scientific Publications. doi:10.1351/goldbook
- McClements, David J. (2008). “Lipid-Based Emulsions and Emulsifiers“. In Akoh, Casimir C.; Min, David B. (eds.). Food Lipids: Chemistry, Nutrition, and Biotechnology. Food Science and Technology (3rd ed.). Boca Raton, Florida: CRC. ISBN 978-1420046649.
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