Is Air A Pure Substance? (Plus Answers to Other Air Questions)

No, air is not a pure substance. It is made up of multiple substances, and some of which are chemically bonded to each other.

In the article that follows, we’ll explain what a pure substance is and why air does not qualify.

Why Isn’t Air A Pure Substance?

First, let’s talk about what a pure substance is.

A pure substance is a material that is made up or only one kind of material. In many cases, this is an element (like gold), or the substance is made up of one kind of compound (like water, which is made up of oxygen bonded to hydrogen).

Next, let’s talk about what “air” is.

For the sake of this discussion, we are assuming that air is the gas that you are breathing when you walk about of your house.

The air that we breath is composed of many substances. It contains oxygen, nitrogen, argon, carbon dioxide, helium, hydrogen, and xenon.

The air that we breath also usually contains some water vapor, though this fluctuates depending where you are in the world and what the weather is like.

And, depending on whether you are near to a large city, to a manufacturing center, or in the vicinity of an active volcano, the air is likely to contain at least some amount of tiny particulate matter that we would consider pollutants.

Now, knowing what a “pure substance” is and what “air” is, can’t you see why it is that air does not qualify?

It is made up of multiple substances.

Could Air Ever Be Considered A Pure Substance?

No, we don’t think so. By definition, air is the gaseous substance that we breath. If the air was separated into its constituent parts, and you breathed only one of those gases (like oxygen, nitrogen, or hydrogen), you wouldn’t survive for long unless that gas was oxygen. (and even then your body wouldn’t function optimally)

And if it were only one of those gases, we would just call them what they are (aka hydrogen), because that isolated gas is not “air.”

If Air Is Not A Pure Substance, What Is It?

Air is considered a heterogeneous mixture. We actually wrote a whole article on this question of whether air was a mixture or a compound, click to check it out.

Is Air Made Of Atoms?

Yes, air is made of atoms. After all, all matter is made up of atoms.

But this is not the end of the story. Air is made up of multiple gaseous substances, like carbon dioxide.

We don’t say that carbon dioxide atoms are a building block of air, because there is no such thing as a carbon dioxide atom. Instead, there is a carbon dioxide molecule, which is formed when one carbon atom and two oxygen atoms are chemically bonded to each other.

The oxygen we breath is not just one oxygen atom at a time, but is in fact two oxygen atoms chemically bonded to each other.

For the most part, almost all of the substances that make up air are atoms that are bonded to other others to form molecules.

Thus you can say that air is made up of atoms, but it is scientifically more accurate if you say that air is made up of many different kinds of molecules.

Is Air Matter?

Yes, air is matter. Matter does not have to be something you can smell or taste or touch to exist.

The air that you breath is made up of millions of atoms, many of which are joined to other atoms to form molecules.

These atoms take up space, they have weight, and they can be converted into liquids and solids under the right conditions.

Is Air A Gas?

Sort of. Air is mostly gas, but not all.

Air is made up of multiple different types of substances that are in a gaseous form, such as nitrogen, oxygen, and carbon dioxide.

But as we discussed above, air is also a host for tiny droplets of water, as well as particulate matter, such as ash or pollution.

These tiny particles, even though they are too small for us to see without a microscope, are not in a gaseous form.

Thus, the air we breath is mostly gas.

But not all.

Is Air Denser Than Water?

No, air is not denser than water. In fact, at sea level, air is 784 times less dense than water. (source)

Is Air Living Or Non-living?

Air is a non-living substance.

It is necessary for most of the life on Earth, but it does not live itself.

Interested in learning more about pure substances and mixtures? Or whether materials like steel, silver, milk, vinegar, blood, and water are considered pure substances or mixtures?

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