Composition of Air: Definition, Properties, Diagram

Composition of Air: We know that one cannot live without air. Air is a mixture of many gases. It is present everywhere around us. In ancient times, it was believed that air is a pure substance, but later experiments proved that air is a mixture of many gases. Do you know which are these gases? In this article, we will learn more about the properties and different components of air in detail.

What is Composition of Air?

Air contains different gases such as nitrogen, oxygen, carbon dioxide and other gases (It includes water vapour, trace gases like argon and helium, hydrogen, smoke and dust particles, etc.) The below diagram gives an idea about the main components of air.

Composition of Air Diagram

The composition of air varies from place to place. For example, the air is thinner on mountains as compared to plains. This is the reason why mountaineers always carry oxygen cylinders with them. Also, the percentage of oxygen in the air may be higher in areas where there is more greenery. In the desert areas, the water vapour content will be significantly lower than the regular areas because of the lack of water in desert areas.

Properties of Air

Air has the following characteristics:  

1. Air can occupy any space
2. There is mass in the air.
3. Heat has an effect on the air.
4. Air exerts a force.
5. It is possible to compress air
6. Altitude has an impact on air.

Composition of Gases in Air/ The Chemical Composition of Air

Let us discuss more some of the major gaseous components of air, one by one:

Nitrogen

It is the major component found in the air. It is the most abundant gas on the earth’s planet too. It is required by plants and animals for their growth. The circulation of nitrogen between these organisms and the atmosphere is called the nitrogen cycle. 

The nitrogen cycle is essential for maintaining productive and healthy ecosystems. Nitrogen present in the air is also used to manufacture fertilisers which helps in the healthy growth of plants. The large percentage of nitrogen in the air also helps in controlling burning, since nitrogen does not support the process of combustion.

Oxygen

Air contains around \(21\% \) of oxygen. It is called the life-supporting gas. Oxygen is necessary for all living organisms because they derive energy from food with the help of oxygen. Respiration is the process of taking in oxygen, using it to make energy (by breaking down food), and then exhaling carbon dioxide. 

Besides breathing, the presence of oxygen is required for combustion (that is, burning of fuels and other substances). Both respiration and combustion processes utilise oxygen and release carbon dioxide in the atmosphere.

Carbon Dioxide

Carbon dioxide makes up a small component of the air around us. It is an important gas for plants as well as animals. Plants use carbon dioxide for making food during the process of photosynthesis. Carbon dioxide is known as a greenhouse gas as it helps to trap heat. The property of trapping heat on the earth’s atmosphere and thus maintaining a comfortably warm temperature is known as the greenhouse effect. The percentage of carbon dioxide in the atmosphere keeps on changing from one place to another. It will be more in polluted areas.

The process of respiration and photosynthesis helps to maintain the balance of oxygen and carbon dioxide in the atmosphere.

Other Gases

Let us discuss about few other gases present in the air:

Water Vapour

The air contains water vapour. It is formed when the water present in the water bodies evaporates due to heat and then it rises up and mixes into the atmosphere. The presence of water vapour in air is important for the water cycle (The cyclic flow of water from the earth to the atmosphere and back to the earth is called as water cycle).

Smoke and Dust Particles

Burning of fossil fuels is considered as one of the main sources of smoke emission in the air. Its composition varies from place to place. Smoke contains a few gases and is often harmful. Dust particles are always present in the air. 

Apart from the gases mentioned above, the air contains the gases such as argon, hydrogen, helium, ozone, etc. in very small amounts.

Composition of Exhaled Air

We know that, air contains the gases like nitrogen, oxygen, carbon dioxide and other trace gases. As our nose cannot filter oxygen from other gases, we inhale the same mixture of air. When we exhale out, the air with the same composition will be given out, but the percentage of carbon dioxide and oxygen changes. This is because, the cells in our body utilizes the oxygen present in the inhaled air and as a result, energy and give out carbon dioxide as a byproduct. The exhaled air hence contains a large amount of carbon dioxide and less amount of oxygen than the inhaled air.

Air Pollution, Composition and Structure of Atmosphere

Air Pollution Air pollution refers to the contamination of air. That is, when unwanted particles and gases mix with air, it is called air pollution. The main causes of air pollution include burning of fuels and the smoke released from industries and vehicles. Pollution is very harmful for us in many ways. That is, it can harm our lungs, can cause heart disease, respiratory diseases, etc. Therefore, it is important to control and reduce the activities that makes the air dirty.

Composition and Structure of the Atmosphere

Atmosphere: Our earth is surrounded by a thin layer of air. This layer is called as the atmosphere. It has five main layers such as troposphere, stratosphere, mesosphere, thermosphere and exosphere. The atmosphere also helps to maintain the right temperature on the earth. It causes the weather change. The air in the atmosphere will get thinner as we go up in the atmosphere.

The Layers of Atmosphere

Our atmosphere has five main layers. Let us discuss them in detail. 

1. Troposphere: It is the first layer of the atmosphere as we go upward. It extends about \({\rm{10}}\,{\rm{km}}\) above the ground. This layer is associated with the weather processes such as cloud formation, thunderstorms, rainfall and snowfall.
2. Stratosphere: It is the second layer of the atmosphere as we go upward. It extends about \({\rm{50}}\,{\rm{km}}\) from the earth’s surface. The ozone layer which protects us from the harmful UV radiations coming from the sun, is present in this layer. 
3. Mesosphere: It is the third layer of the atmosphere as we go upward. It extends around \({\rm{80}}\,{\rm{km}}\) from the earth’s surface. The burning of meteorites on entering from space occurs in this layer.
4. Thermosphere: It is the fourth layer which is found above the mesosphere. It extends between \({\rm{80 – 450}}\,{\rm{km}}\) from the earth’s surface. This layer can help in radio transmission.
5. Exosphere:  It is the upper most layer of the atmosphere. It has very thin air. The trace gases like helium and hydrogen float into the space from here.

Summary

In this article, we learnt about the air and the atmosphere. We are now familiar with the different components of air. That is, the air is a mixture of many gases such as nitrogen, oxygen, carbon dioxide, water vapour and other trace gases. The composition of air varies from place to place. Each of the components of air plays a major role in different life processes too. The atmosphere is the blanket of air that surrounds the earth. Our atmosphere will get polluted due to the introduction of harmful gases into the air.

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FAQs on Composition of Air

Q.1. What is the composition of air?
Ans: Air is a mixture of many gases such as nitrogen, oxygen, carbon dioxide, other gases (It includes water vapour, trace gases like argon and helium, hydrogen, smoke and dust particles, etc.). The composition of air varies from place to place.

Q.2. What is the composition of air in the atmosphere?
Ans: The air in the atmosphere is made of \({\rm{78\% }}\) nitrogen, \({\rm{21\% }}\) oxygen, \({\rm{0.3\% }}\) carbon dioxide and \({\rm{0.7\% }}\) of other gases (such as argon and helium, hydrogen, smoke and dust particles, etc.) in trace amounts.

Q.3. Draw a diagram showing the composition of air.
Ans: Air is a mixture of many gases. That is, it contains \({\rm{78\% }}\) nitrogen, \({\rm{21\% }}\) oxygen, \({\rm{0.3\% }}\) carbon dioxide and \({\rm{0.7\% }}\) of other gases such as argon and helium, hydrogen, smoke, dust particles, etc. in trace amounts. A diagram showing the composition of air can be given as,

Q.4. Who discovered the composition of air?
Ans: In ancient times, it was believed that air is a pure substance but Joseph Priestly, in \(1774\) showed that air is a mixture of many gases. Later experiments done by the chemists like Antoine Lavoisier, Henry Cavendish, etc. proved that, air is a mixture of many gases.