The Difference Between Heterogeneous and Homogeneous Mixtures

The terms heterogeneous and homogeneous refer to mixtures of materials in chemistry. The difference between heterogeneous and homogeneous mixtures is the degree to which the materials are mixed together and the uniformity of their composition.

A homogeneous mixture is a mixture in which the components that make up the mixture are uniformly distributed throughout the mixture. The composition of the mixture is the same throughout. There is only one phase of matter observed in a homogeneous mixture at a time. So, you wouldn't observe both a liquid and a gas or a liquid and a solid in a homogeneous mixture.

Homogeneous Mixture Examples

There are several examples of homogeneous mixtures encountered in everyday life:

• Air
• Sugar water
• Rainwater
• Vodka
• Vinegar
• Dishwashing detergent
• Steel

You can't pick out components of a homogeneous mixture or use simple mechanical means to separate them. You can't see individual chemicals or ingredients in this type of mixture. Only one phase of matter is present in a homogeneous mixture.

A heterogeneous mixture is a mixture in which the components of the mixture are not uniform or have localized regions with different properties. Different samples from the mixture are not identical to each other. There are always two or more phases in a heterogeneous mixture, where you can identify a region with properties that are distinct from those of another region, even if they are the same state of matter (e.g., liquid, solid).

Heterogeneous Mixture Examples

Heterogeneous mixtures are more common than homogeneous mixtures. Examples include:

• Cereal in milk
• Vegetable soup
• Pizza
• Blood
• Gravel
• Ice in soda
• Salad dressing
• Mixed nuts
• Bowl of colored candies
• Soil

Usually, it's possible to physically separate components of a heterogeneous mixture. For example, you can centrifuge (spin out) solid blood cells to separate them from the plasma of blood. You can remove ice cubes from soda. You can separate candies according to color.

Telling Homogeneous and Heterogeneous Mixtures Apart

Mostly, the difference between the two types of mixtures is a matter of scale. If you look closely at sand from a beach, you can see the different components, including shells, coral, sand, and organic matter. It's a heterogeneous mixture. If, however, you view a large volume of sand from a distance, it's impossible to discern the different types of particles. The mixture is homogeneous. This can seem confusing!

To identify the nature of a mixture, consider its sample size. If you can see more than one phase of matter or different regions in the sample, it is heterogeneous. If the composition of the mixture appears uniform no matter where you sample it, the mixture is homogeneous.