Flame

key notes :

Zones of Candle Flame

When you light a candle a combustion reaction takes place with the wax of the candle which is the fuel and the air which contains oxygen. The flames are the are in which this combustion reaction is taking place. The release of heat and light energy from this exothermic reaction happens through the flame.
Starting from the base of the flame, a flame has four zones.
1. Inner Part

  • This is the innermost part of the flame. 
  • It is the part closest to the wick. 
  • You might assume that this is the hottest part of the flame. However, it is the least hot. 
  • This is the black part of the flames that contains unburnt particles of the carbon from the wick i.e. unburnt fuel.

2. Middle Part 

  • This is the biggest part of the flame. 
  • The colors in this are varying shades of yellow and orange. 
  • This is the luminous flame because it emits light. 
  • This part is also not extremely hot. This is because this part gets a limited supply of oxygen. 
  • Incomplete combustion takes place here which is why it burns orange and is luminous.

3. Outer Part

  • This is the hottest part of the flame. 
  • This part has an unlimited supply of oxygen. So complete combustion takes place here. Hence it is the hottest part of the flame. 
  • Also, this part of the flames burns with a blue color. 
  • It is the non-luminous, i.e. does not emit light.

key idea :-

What is a Flame?

  • A flame is a visible, gaseous part of a fire.
  • It emits light and heat as a result of the combustion process.
  • Flames can vary in size, color, and intensity depending on the fuel and conditions.

Components of a Flame:

  1. Inner Blue Cone (Zone of Complete Combustion):
    • This is the central part of the flame.
    • Here, fuel (such as gas or vapor) reacts with oxygen to release energy, producing carbon dioxide and water vapor.
    • The combustion is efficient and complete, resulting in a blue color due to high temperature.
  2. Outer Yellow Cone (Zone of Incomplete Combustion):
    • Surrounds the inner cone.
    • In this zone, there is insufficient oxygen, leading to incomplete combustion.
    • Carbon particles are released, causing the yellow color of the flame.
    • This zone is cooler than the inner cone.
  3. Non-Luminous Zone (Near the Base):
    • This is where fuel vapor is released and starts to mix with oxygen.
    • It is not usually visible, as there is not enough heat to cause visible light emission.

Factors Affecting Flame Color:

  • The color of a flame can indicate the type of fuel being burned.
  • Different elements and compounds emit characteristic colors when heated:
    • Copper: Green flame
    • Sodium: Yellow flame
    • Lithium: Red flame

Uses of Flames:

  • Flames are used in various applications, such as:
    • Cooking: Flames from stoves and ovens heat food.
    • Heating: Flames provide warmth in fireplaces, heaters, and furnaces.
    • Lighting: Flames in candles, oil lamps, and gas lamps provide light.
    • Welding and Cutting: Flames with intense heat are used in metalworking.

Fire Safety:

  • Flames can be dangerous if not controlled properly.
  • Always exercise caution when dealing with open flames.
  • Keep flammable materials away from flames.
  • Use fire extinguishers and follow safety guidelines to prevent accidents.

Interesting Fact:

  • Fire is a chemical reaction called combustion, involving a fuel, oxygen, and heat.

Remember, these key points are meant to provide a basic understanding of the topic “Flame” for Grade 8 students. You can expand upon these points based on the specific curriculum or educational standards in your region.

Let’s practice!