Combustion and Flames Class 8 Notes - Chapter 6

CBSE Class 8 Chapter 6 notes – Combustion and Flames

List of Content
Combustion
Types of Combustion
Important Questions

Combustion

Combustion is a chemical process in which a substance reacts with oxygen and liberates heat. Substances that undergo combustion are said to be combustible. Sometimes, during combustion light is given off as flames or a glow. Oxygen in the air is essential for combustion. The lowest temperature at which a combustible substance catches fire is known as the ignition temperature. The substances with low ignition temperature and can easily catch fire are known as inflammable substances. Alcohol, petrol and diesel are a few examples of inflammable substances. While extinguishing a hazardous fire, water is poured on the fire because water cools the temperature of combustible material below ignition temperature. Although, we cannot control a fire involving electrical equipment and gas.

Types of Combustion

Combustion is of three types as follows:

    • Rapid Combustion – Type of combustion in which the combustible burns rapidly and produces light and heat. Example -When a burning matchstick is brought close to a gas burner, the gas immediately starts burning with the production of heat and light.
    • Spontaneous Combustion – Type of combustion in which the combustible bursts into flames without any apparent cause. Example – Burning of phosphorus in the air at room temperature
    • Explosion – Type of combustion in which a large amount of gas is liberated with the production of sound, light and heat. Example – When firecrackers are exploded

The substances that vapourise during burning, give flames. There are three different zones in a flame – dark zone, luminous zone and non-luminous zone.

Combustion And Flame Class 8 Important Questions

  1. List conditions in which combustion takes place
  2. Why isn’t water used to control a fire involving electrical equipment
  3. Explain how carbon dioxide is able to control fire.

Learn more about candle flame and fuel efficiency and other related topics including NCERT class 8 science notes, at BYJU’S.

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