Page 71 - Science Class 08

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Combustion and Flame

• Combus on • Supporter of Combus on • Types of Combus on
• How to ontrol ire? C F • Flame
• The ffect of urning of uels on E B F Environment

The discovery of fire was perhaps the most hydrocarbons, they release carbon dioxide and
important discovery of early man. It was the water on burning in adequate supply of oxygen.

first step towards the evolu on of civilisa on. Heat and light are also produced during the
But, the early man did not know the cause of process of combus on. When methane is burnt
fire. Since, then fire has been used for various in the presence of adequate supply of air,
purposes. We can even say that fire is the basis carbon dioxide and water are formed and
of modern development. But a er the energy is released in the form of heat and light.
discovery of oxygen, Antoine Lavoiser explained CH + 2O Õ CO + 2H O + energy
4
2
2
2
that fire was the result of a chemical reac on Methane Oxygen Carbon water
between a burning substance and oxygen. dioxide
The three things needed to carry on the process But, when methane is burnt in short supply of
of burning are: oxygen, methane does not burn completely.
v Combus ble substances (a substance This is called incomplete combus on. During
which can burn) incomplete combus on, methane releases
carbon monoxide, water and energy.
v Oxygen
2CH + 3O Õ 2CO + 4H O + energy
v Heat 4 2 2
Methane Oxygen Carbon water
Absence of any one of these things will put monoxide
out fire.
Condi on Required for the Process of
COMBUSTION Combus on

Combus on is the process of burning of There are three condi ons for the combus on
substances with the evolu on of heat and light to take place.
since most of the fuels are made up of

Science-8 71