Short Answer

Combustion is a chemical reaction in which a substance reacts rapidly with oxygen to produce heat and often light. It is commonly known as burning. Combustion reactions release energy, making them important in daily activities such as cooking, lighting, and running vehicles.

During combustion, fuels like wood, coal, petrol, or natural gas react with oxygen to form new products such as carbon dioxide and water. Combustion can be complete or incomplete depending on the amount of oxygen available. Complete combustion produces more heat and cleaner products.

Detailed Explanation :

Combustion

Combustion is a chemical process in which a substance reacts rapidly with oxygen to release a large amount of heat and sometimes light. This reaction is commonly seen when a fuel such as wood, paper, petrol, kerosene, or coal burns in the presence of air. Combustion is one of the most important chemical reactions because it provides the energy needed for cooking, heating, transportation, and industrial work.

Combustion is an exothermic reaction, which means it releases energy. The products formed depend on how much oxygen is available. If enough oxygen is present, the fuel burns completely and produces carbon dioxide and water. If oxygen is limited, incomplete combustion occurs, producing carbon monoxide, soot, and less heat. Understanding combustion helps explain fire safety, engine functioning, and energy production.

1. Conditions Required for Combustion

For combustion to occur, three essential conditions must be met:

1. a) Presence of Fuel

A substance that can burn, such as wood, paper, petrol, LPG, or coal.

1. b) Presence of Oxygen

Oxygen from the air supports combustion. Without oxygen, burning stops.

1. c) Sufficient Heat (Ignition Temperature)

The fuel must be heated to a minimum temperature for combustion to begin.
This is called the ignition temperature.

If any of these three conditions are removed, combustion will not take place.

2. Types of Combustion
3. a) Rapid Combustion

Occurs quickly and produces heat and light.
Example: Burning of LPG or dry paper.

1. b) Spontaneous Combustion

Occurs without external heating.
Example: Phosphorus catching fire in air.

1. c) Slow Combustion

Occurs very slowly without flame.
Example: Rusting of iron (very slow form of oxidation).

1. d) Complete Combustion

Happens when adequate oxygen is available.
Example:
Fuel + Oxygen → Carbon dioxide + Water + Heat

Produces more heat and no harmful gases.

1. e) Incomplete Combustion

Happens when oxygen is limited.
Example:
Fuel + Limited Oxygen → Carbon monoxide + Soot + Less heat

Carbon monoxide is poisonous and dangerous.

3. Products of Combustion

The products depend on the type of fuel and oxygen supply:

1. a) Carbon dioxide (CO₂)

Formed during complete combustion of carbon-based fuels.

1. b) Water vapour (H₂O)

Released as steam.

1. c) Carbon monoxide (CO)

Formed during incomplete combustion.

1. d) Soot (carbon particles)

Black particles seen when something burns incompletely.

1. e) Heat and Light

Energy released during the reaction.

4. Everyday Examples of Combustion

Combustion is involved in many daily activities:

1. a) Cooking Food

Gas stoves burn LPG through rapid combustion.

1. b) Lighting Fireplaces and Candles

Wax and wood undergo combustion to provide heat and light.

1. c) Vehicle Engines

Petrol or diesel burns inside engines to power vehicles.

1. d) Burning of Fireworks

Metal salts burn to produce colourful flames.

1. e) Industrial Furnaces

Coal and natural gas are burned for heating and manufacturing.

5. Importance of Combustion

Combustion is essential for:

1. a) Energy Production

Most energy used in homes and industries comes from burning fuels.

1. b) Transportation

Automobiles, trains, airplanes, and ships use combustion engines.

1. c) Heating and Cooking

Burning fuels provide warmth and help prepare food.

1. d) Industrial Processes

Metal extraction, cement production, and chemical manufacturing depend on combustion.

However, combustion also produces pollutants such as carbon monoxide, nitrogen oxides, and soot. Therefore, understanding combustion helps control air pollution and improve fuel efficiency.

6. Safety Precautions in Combustion

Because combustion involves heat and fire, it must be handled carefully.

1. a) Keep Flammable Objects Away

Paper, cloth, and aerosols should not be near flames.

1. b) Ensure Good Ventilation

To avoid carbon monoxide buildup during incomplete combustion.

1. c) Store Fuels Properly

Petrol, LPG, and kerosene should be kept in safe containers.

1. d) Use Fire Extinguishers

Removing oxygen, cooling the fuel, or cutting off heat stops combustion.

Understanding these precautions helps prevent accidents and fire hazards.

Conclusion

Combustion is a chemical reaction in which a substance reacts with oxygen to release heat and light. It requires fuel, oxygen, and ignition temperature to begin. Combustion can be complete or incomplete depending on the oxygen supply. It is vital for cooking, heating, transportation, and energy production. At the same time, controlling combustion is important for safety and reducing pollution. Combustion plays a major role in daily life, industry, and the natural environment.