Is Air a Mixture? (Or A Compound? Or An Element?)

Yes, air is a mixture because it is make up or more than one substance and those substances can be separated.

Want to learn more, or understand why people are confused about whether air is a mixture or a compound? We’ll explain in the article below.

Why Is Air a Mixture?

First, let’s talk about what a mixture is, as this is key to understanding the answer to our question.

What is a Mixture?

Chemically speaking, a mixture is a substance or material that is made up of distinct materials that are not chemically bonded to each other. A mixture can be separated back into its original components. And those original components retain their original characteristics.

Some obvious examples of mixtures that you might encounter in the world are:

  • Dirt
  • Mud
  • Sand
  • Salad
  • Cement
  • Gasoline

Next, we’ll need to break down what air is, exactly.

What is Air?

Air is an invisible gas that surrounds us and the Earth.

In air, you will find oxygen, nitrogen, argon, carbon dioxide, neon, helium, krypton, hydrogen, and zenon. (source)

Depending on where you are in the world, the air probably also contains some water vapor, as well as some particulate contaminants (think pollution).

All of the various molecules that make up air bounce around freely, more quickly when the temperature of the air is warmer than they do when it is colder.

Those molecules are not connected to each other, unless they are already bonded in some way (like carbon dioxide).

They all retain their original physical characteristics even mixed up with the other elements found in air.

You can remove any one of these substances from the air if you have the equipment and the know-how.

Separating one substance from the group of the rest does not require that you break any chemical bonds or force a reaction (like you would need in order to separate the carbon from the oxygen in carbon dioxide).

Can You See Why Air Would Be Considered a Mixture?

Air is considered a mixture because it is made up of multiple gases that are not bonded to each other chemically, that retain their original characteristics, that can be separated from the group without breaking any chemical bonds.

Is Air a Homogeneous Mixture?

We think this depends on what you consider to be “air” and the sample of air you are examining.

A homogeneous mixture is a mixture where the chemical composition of the material is the same, regardless of where you take your sample.

A heterogeneous mixture is one where the composition is not consistent throughout. It may even contain substances that are in different phases like solid and liquid (ice water).

If you are taking a sample of air that is just air (meaning the gaseous components of air, like oxygen, carbon dioxide, nitrogen, etc), then the sample is going to be a homogeneous mixture. The amount and distribution of the various substances will be consistent.

For example, if you were to sample air in Norway, it will have the same amount of oxygen that an air sample taken from Australia contains.

Quick question though: does your definition of air include the water vapor or pollutants/impurities that are often found in air?

Not sure what I mean by pollutants? Think of the smoke that results from a wildfire, or the exhaust expelled by vehicles.

If you think of air as being a mixture of all the gases only, then air itself is a homogeneous mixture that is then mixed in with water vapor and particles.

If you think of air as the substance that you breath in when you walk outside, inclusive of all the stuff that exists in it as a result of weather and humans, then the air is a heterogeneous mixture.

After all, there are differing levels of water vapor in the air depending on where in the world you live, and the amount of pollutants in the air will also change depending on the concentration of humans/vehicles.

The mixture samples in Columbia vs Austria wouldn’t be consistent, and would contain more or less of other substances.

This is a great question, and one that you could argue with your chemistry/biology teacher about.

Is Air a Compound?

No, air is not a compound.

Scientifically speaking, a compound is formed when one or more substances are bonded together chemically.

While the combined substance may retain some of its physical properties (like it is still a gas as it was before when the substances were separate), but in many cases the physical properties are different.

Water (H2O) is a good example of how the physical properties of the compound differ from the substances that joined together to make it (oxygen gas and hydrogen gas).

It is difficult to separate the chemically bonded materials.

Air is not a compound because the substances that make up air (like oxygen, nitrogen, and carbon dioxide) are not chemically bonded to each other.

Out in the world, these molecules bounce around and off each other, all mixed up, but never connecting.

The individual substances can be easily separated from the whole, and they all retain their original source physical properties.

This is why air is not a compound.

Is Air an Element?

No, air is not an element.

An element is a material or substance that is made up of only one kind of atom. Gold is a good example of a well-known substance in the world that is an element. All of its atoms are gold atoms, and there are no other kinds of atoms mixed in to make up that substance.

(Yes, we know that gold can definitely have impurities, and gold jewelry certainly has other substances mixed into it to make it harder and more durable. That doesn’t change what gold is scientifically.)

Air is made up of multiple substances, with many different kinds of atoms. Some of the components of air are elements themselves.

But air is not an element.

Interested in learning more about pure substances and mixtures? Or whether materials like chocolate, water, wood, coffee, honey, sand, aluminum foil, or baking soda are considered pure substances or mixtures?

Check out our Knowledge Vault for our latest posts as we dig deeper and learn more about the world we live on.