Combustion and Flame

Science Class 8 : Chapter 06

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Quick Revision : Combustion and Flame

  • Combustion: A chemical process where a substance reacts with oxygen to give off heat.
  • Three essential requirements: Fuel, oxygen (air), and heat to reach ignition temperature.
  • Ignition Temperature: The lowest temperature at which a substance catches fire.
  • Inflammable Substances: Have very low ignition temperature and catch fire easily (petrol, alcohol, LPG).
  • Types of Combustion: Rapid, spontaneous, and explosion.
  • Fire Control: Remove fuel, oxygen, or reduce temperature below ignition point.
  • Fire Extinguishers: Water, COβ‚‚, foam, dry chemical powder based on fire type.
  • Flame Structure: Outer zone (hottest, complete combustion), middle zone (luminous, partial combustion), inner zone (dark, unburnt vapours).
  • Fuel Efficiency: Measured by calorific value (kJ/kg). Higher calorific value means better fuel.
  • Harmful Products: Unburnt carbon particles, CO, COβ‚‚, SOβ‚‚, oxides of nitrogen causing pollution, acid rain, global warming.

Questions

Chapter Summary : Combustion and Flame

What You Will Learn: This chapter covers the chemical process of combustion, conditions required for burning, types of combustion, fire control methods, structure of flame, fuel efficiency, and environmental impacts of burning fuels.

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