Combustion and Flame : Flame


Candles produce light by releasing heat and all the turn on the candle produces come from a chemical reaction known as combustion in which wax reacts with oxygen in the air to produce carbon dioxide. The substances that vaporize while burning produces the flame. Kerosene oil and molten wax are the two substances that are responsible for producing flame while burning. Flame is defined as the area of combustion of a combustible substance. Substances that do not vaporize during burning, do not produce the flame.

Structure of candle flame

In a general candle, flame color depends on the amount of oxygen, temperature, and nature of the substance that undergoes combustion. There are two types of flames: luminous and nonluminous flame. A luminous flame is a flame that provides light and is in bright yellow color. A luminous flame is a flame that does not get sufficient amount of oxygen and therefore, undergoes incomplete combustion whereas a nonluminous flame is much hotter and colorless and it undergoes complete combustion in the presence of sufficient oxygen. In a candle flame, a quarter of the energy created is released as heat.

A candle flame consists of several different zones with different temperatures. Colors tell us the temperature of the flame.

  • Outer zone
  • Middle zone
  • Inner zone

The outermost zone is the hottest among all zones and is blue in color, and this is due to complete combustion. It is the non-luminous part of the flame.

The middle zone of the candle flame is moderately hot and is yellow in color, and partial combustion of fuel takes place. It is bright part of the fire.

The innermost zone of the flame is the least hot and is black in color. This is due to the presence of unburnt wax vapors.

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Combustion and Flame : Fire Control