Combustion is the process of burning a substance in the presence of oxygen, producing light and heat. It involves exothermic chemical reactions between a fuel and an oxidant. Burning produces light and heat. LPG is useful for cooking. Combustible substances burn to produce light and heat, while non-combustible substances do not. Spontaneous combustion occurs without an ignition source through heat buildup during oxidation. Rapid combustion releases a lot of heat and light quickly, and sometimes gas.

1. By Jayanarayan.J,
Mars House

2. WHAT IS COMBUSTION ?
Combustion is defined as the process of burning of a
substance in the presence of air or oxygen with the
liberation of light and heat.
Or
Combustion or burning is the sequence of exothermic
chemical reactions between a fuel and an oxidant
accompanied by the production of heat and conversion of
chemical species.

3. LETS SEE SOME IMAGES.

4. WHAT DO BURNING A SUBSTANCE PRODUCE ?
• Burning a substance produces
Light and heat
HOW IS LPG USEFUL TO US?
• LPG is used for Cooking

5. COMBUSTIBLE SUBSTANCES
 Substances that burn in air to produce light and heat
are called combustible substances
 Eg- Paper , Wood , Kerosene , LPG .

6. NON-COMBUSTIBLE SUBSTANCES
 Substances that do not burn in air to produce light and
heat are called combustible substances
 Eg-Water , Sand , Glass , Cement .

7. SPONTANEOUS COMBUSTION
 Spontaneous combustion is a type of combustion which occurs
without an external ignition source. It is usually a slow process
that can take several hours of decomposition/oxidation with heat
build up to a point of ignition.
• Coal can spontaneously ignite when exposed to oxygen which causes it to
react and heat up when there is insufficient ventilation for cooling.
• Pyrite oxidation is often the cause of coal spontaneous ignition in old Mine
tailings.
• Pistachio nuts are highly flammable when stored in large quantities, and are
prone to self-heating and spontaneous combustion.
• Large cow manure piles can spontaneously combust during conditions of
extreme heat.

8. RAPID COMBUSTION
It’s a Type of combustion where lot of heat and
light is released in a short time span.
Sometimes, a large volume of gas is liberated
in combustion besides the production of heat
and light.

9. COMPLETE COMBUSTION
 In complete combustion, the reactant burns in oxygen, producing
a limited number of products. When a hydrocarbon burns in
oxygen, the reaction will only yield carbon dioxide and water.
When elements are burned, the products are primarily the most
common oxides. Carbon will yield carbon dioxide, nitrogen will
yield nitrogen dioxide, sulfur will yield sulfur dioxide, and iron will
yield iron(III) oxide.

10. INCOMPLETE COMBUSTION
 Incomplete combustion occurs when there isn't enough oxygen to
allow the fuel to react completely to produce carbon dioxide and
water. It also happens when the combustion is quenched by a
heat sink such as a solid surface or flame trap.

11. EXPLOSION
The sudden evolution of large quantities of gas
creates excessive pressure that produces a
loud noise. Combustion need not involve
oxygen; e.g., hydrogen burns in chlorine to
form hydrogen chloride with the liberation of
heat and light characteristic of combustion.