Structure Of A Flame

key notes :

Definition of a Flame

  • A flame is the visible, gaseous part of a fire that emits light and heat. It is produced when a substance burns.

Parts of a Flame

A flame has three distinct regions, each with different characteristics:

Innermost Zone (Dark Zone)

  • Closest to the wick or fuel source.
  • Contains unburnt wax vapors or fuel.
  • Does not emit light and is the least hot part of the flame.

Middle Zone (Luminous Zone)

  • Yellow and bright in appearance.
  • Incomplete combustion occurs due to limited oxygen.
  • Produces soot (tiny carbon particles) and emits light.

Outermost Zone (Non-Luminous Zone)

  • Blue in color and barely visible.
  • Complete combustion occurs here due to ample oxygen.
  • Hottest part of the flame.

Types of Flames

  • Luminous Flame: Produces light, occurs due to incomplete combustion, and is yellow (e.g., candle flame).
  • Non-Luminous Flame: Does not produce much light, occurs due to complete combustion, and is blue (e.g., Bunsen burner flame).

Temperature Distribution in a Flame

  • The hottest part is the outermost zone.
  • The coolest part is the innermost zone.

Flame Colors and Their Causes

  • Yellow Flame: Caused by incomplete combustion and the glow of carbon particles.
  • Blue Flame: Indicates complete combustion with sufficient oxygen.

Importance of Oxygen

  • Oxygen availability determines the type and efficiency of combustion in a flame.

Applications of Flames

  • Used in cooking, welding, and scientific experiments (e.g., Bunsen burner).

Safety Precautions

  • Ensure proper ventilation when using flames to avoid accumulation of harmful gases.
  • Avoid placing flammable materials near an open flame.

Practical Demonstration

  • Observe a candle flame to identify its zones.
  • Use a Bunsen burner to compare luminous and non-luminous flames.

Let’s practice!