What Is The Composition Of Air?

Air is important to all forms of life in several ways. Its pressure retains the shape of objects on the surface of earth. Air provides us with the life giving element – oxygen, which is responsible for respiration and combustion. The importance of nitrogen in the air is in diluting the oxygen to moderate the process of burning and respiration. Oxygen is very reactive and without nitrogen everything would be in flames. Air is essential for burning and combustion and only oxygen of the air is used up in these processes.

In earlier times, air was thought to be simple substance and was called an element. In the eighteenth century, it was shown that air is a mixture of two major components – nitrogen and oxygen. Now we know that air contains different gases in the following rough proportions –

Nitrogen (N2): 78.1%
Oxygen (O2): 20.29%
Carbon dioxide (CO2): 0.03%
Water vapour: 0.4%
Inert gas: 0.95%
Dust particles, sulphur oxides, nitrogen oxides, etc.: variable