Page 1 - LN

SAI International School

Subject - Chemistry
Class - VIII
Topic – COMBUSTION AND FLAME
Sub-Topic- Types of combustion, Calorific Value and Flame

LESSON NOTES

Types of Combustion

There are three types of combustion to study.

1. Rapid combustion.
The combustion reaction in which a large amount of
heat and light are produced in a short time is called
rapid combustion.
For example, when we bring a lighted match stick
near the burner of a gas stove in the kitchen, the
cooking gas starts burning at once producing a
lot of heat and some light.

2. Spontaneous combustion
The combustion reaction which occurs on its own (without
the help of any external heat) is called spontaneous
combustion. Un spontaneous combustion, the substance
suddenly bursts into flames and starts burning without
being heated. It takes place at room temperature.

3. Explosive combustion
A very fast combustion reaction in which a large amount
of heat, light, and sound is produced, is called explosive
combustion. A large amount of gasses is also released
quickly. Because of the rapid expansion of these gases’
an explosion occurs.
For example, the burning of firecrackers.

Fuels
A material that is burnt to produce heat is called fuel. Some of the common fuels are
wood, coal LPG, etc.
Fuels can be found in all three states.
Examples of solid fuels are wood, charcoal, coke, etc. Liquid fuels are kerosene, petrol,
etc.
Gaseous fuels are natural gas, petroleum gas, biogas, etc.

Calorific Value
Different fuels produce different amounts of heat on burning. Some fuels produce more