Is CO2 Heavier Than Air? What Proves CO2 Is Heavier Than Air 

Is CO2 Heavier Than Air

Scientists have had their arguments with supporting claims and explanations on which gas is heavier. Is it true to say that CO2 is heavier than air? 

The functions of the gas explain why carbon dioxide is heavier than air. The CO2 weighs 44 grams per mole, while oxygen weighs 2 grams per mole. 

Carbon dioxide has two different atoms: 1 carbon atom and two oxygen atoms. On the other hand, oxygen only has two oxygen atoms. The atoms and weight of carbon dioxide make it dense and heavier than oxygen.

What does the comparison of carbon dioxide and air make you conclude? Air contains various elements like gases, and carbon dioxide is one of the gases in the air. 

This should enlighten you that in this case, the comparison is between CO2 and oxygen, which comprise the major gases in the air. 

So, is CO2   heavier than air?

Kindly note that air refers to oxygen gas to avoid confusion. C02  gas is much denser (with a density of 1.977 kg/m3) than air, making it heavier than air.

Here are applications of CO2 that support the idea of it being heavier than air. 

Why Do Fire Extinguishers Use CO2? 

Carbon dioxide is used in fire extinguishers because it is heavier than oxygen and does not support burning. 

CO2 characteristic feature of being heavy enables it to form a blanket over fires. The blanket formed cuts the supply of oxygen hence extinguishing the fire.

You have probably come across the carbon dioxide and o2 tests in a chemistry lab. In the oxygen test, the gas relights a glowing wooden splint. In the CO2 test, the gas puts off a lighting wooden splint.


CO2 does not easily mix with oxygen and nitrogen. This is why most of the percentage of carbon dioxide falls to the ground. It either falls deep into the sea levels or is absorbed by plants which helps with photosynthesis. 

Other Uses of CO2

1. Food preservation:

Since carbon dioxide does not support life, it preserves canned foods and drinks. The presence of bacteria is the reason why food spoils. However, bacteria need oxygen for their survival. 

Covering foods with a coat of carbon dioxide prevents any form of life, hence dealing with bacteria. This enables food and drinks companies to preserve their products for years.

2. As a refrigerant:

Solid carbon dioxide, also called dry ice, is used as a refrigerant because of its characteristic feature of sublimation. The process involves changing solids directly into gaseous states. 

However, you should note that hot CO2 gas is lighter than air. When carbon dioxide burns together with other gases, it will be lighter than air, forcing it to rise into the atmosphere. This is what happens with the exhaust gases from petrol and diesel automobiles. 

Yet another reason why ventilation spaces in buildings are on the upper part of the building. 

We breathe out CO2 that is lighter than the air, which causes it to rise and escape through the ventilation spaces on the upper part of the building.  


Air is a mixture of various gases and vapors. However, scientists commonly compare oxygen and CO2.

You should understand that carbon dioxide is a dangerous gas. Any tests that involve the gas should be conducted in labs by qualified individuals or under the supervision of a qualified individual.  


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