What is in air
Air is a uniform mixture of gases.
The air we breathe
Air is all around us. It is made of several gases.
Is air one substance or a mixture?
What this lesson covers
The idea
Air is a uniform mixture mainly of nitrogen (about 78%), oxygen, argon, carbon dioxide and water vapour; oxygen supports life and combustion, while nitrogen takes no part in combustion.
The air we breathe
Air is all around us. It is made of several gases.
Is air one substance or a mixture?
- A mixture of several gases
- One single gas
- A liquid
Parts of air
Open each tab.
Air is a uniform mixture
Air is a uniform mixture of mainly nitrogen, oxygen, argon, carbon dioxide and water vapour. Lime water turning milky when exposed to air shows that air has carbon dioxide.
Air is a uniform mixture of mainly nitrogen (about 78%), oxygen, argon, carbon dioxide and water vapour. Oxygen supports life and combustion. Nitrogen takes no part in combustion.
Notes
Air is a uniform mixture: about 78% nitrogen, plus oxygen, argon, carbon dioxide and water vapour.
Check yourself
Air is a …
About what percent of air is nitrogen?
Answer: 78 %
Nitrogen is about 78% of air.
Which gas in air helps in combustion?
Lime water turns milky when exposed to air. This shows that air has …
- uniform mixture of gases — correct. Yes!
- single gas. Air has several gases mixed together.
- compound. Air is a mixture of gases that do not react to make a compound.
- Nitrogen. Nitrogen takes no part in combustion.
- Oxygen — correct. Yes!
- Argon. The gas that helps combustion is oxygen.
- only nitrogen. Lime water turns milky with carbon dioxide.
- only oxygen. The milkiness shows carbon dioxide.
- carbon dioxide — correct. Yes!