Terms Used in Combustion

‘Combustion’ is a chemical process in which a substance burns.

In this, the substance combines with oxygen to give off heat.

For instance, when a paper burns it undergoes combustion to produce heat and light

Similarly, wood burns to produce heat and light along with the formation of carbon dioxide and water

However, all substances do not catch fire as easily as paper. And there are some substances which do not burn at all.

For example, if we try lighting up stone and sand, we find that they do not undergo combustion.

With that we can divide substances into two types: ones which undergo combustion and ones which do not.

Substances which undergo combustion are called combustible substances.

While substances which do not undergo combustion are called non combustible substances.

Paper, coal, LPG, wood, charcoal, kerosene are all undergo combustion and are examples of Combustible substances.

And sand, stones, glass are substances which do not undergo combustion and are examples of non- combustible substances.

Also, during the combustion of some combustible substances the amount of heat generated if enormous.

In such a case, energy generated from a combustible substance can be used to run vehicles.

Such a combustible substance which produces a lot of heat is also called a fuel.

We use different kinds of fuel in our daily life

Fuels such as LPG or kerosene are burnt at homes to cook food.

While fuels like petrol, diesel, CNG are used to power vehicles.

However, the combustion processes which make our lives so much easier: from cooking food to powering vehicles

Can not take place under all conditions. Here, we will look into essential condition for combustion to take place.

Let us do an activity: We have two lighted candles with us

And we prepare a set up like this:

Even after a while, we find that the first candle keeps burning while the second stops burning

This is because in the first set up there is a constant circulation of oxygen or air, and the candle keeps burning till the wax reaches its end.

While in the second set up, the supply of air is limited. Once all the air inside is used during burning, the candles extinguishes.

This activity implies that for combustion to take place oxygen is essential.


In the process of combustion, a substance reacts with oxygen to give off heat

Paper, coal, LPG, wood, charcoal, kerosene are the examples of Combustible substances.

Substances like stone, sand, glass which do not undergo combustion are non-combustible substances.

Substances which on burning produce a lot of heat are also called fuels.

Oxygen is essential for any combustion process to take place.

The end