Combustion and Flame

Combustion and Types of Combustion

Combustion is a chemical process or a reaction between Fuel (Hydrocarbon) and Oxygen. When fuel and oxygen react it releases the heat and light energy. Heat and light energy then result in the flame. So, the formula for Combustion reaction is Hydrobcarbon + Oxygen = Heat energy. Combustion is used in car motors and rocket engines and many other machineries. There are 5 different types of combustion. Let us learn about combustion and types of combustion.

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What is Combustion?

Combustion is actually a scientific term for burning. We are all aware of burning, but did you know that burning is actually a chemical reaction? Combustion is a chemical process where any fuel has a reaction with air (oxidant) to produce heat energy.

And when this heat energy release it will also produce light in the form of a flame. This is the visible part of the reaction, the flames. The general exothermic reaction of combustion can be expressed as:

Hydrocarbon + Oxygen → Carbon Dioxide + Water + Heat Energy

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Examples of Combustion

  • Burning of Wood or Coal to heat your home
  • Burning of Petrol or Diesel to run your Car
  • Combustion of Natural Gas or LPG to cook for on your stovetop
  • For the production of energy in thermal power plants
  • Fireworks

Types of Combustion

Types of Combustion

1] Complete Combustion

One of the types of combustion is Complete Combustion. Complete combustion occurs in an unlimited supply of air, oxygen in particular. Also, complete combustion is also known as clean combustion. Here the hydrocarbon will burn out completely with the oxygen and leave only two byproducts, water, and carbon dioxide.

An example of this is when a candle burns. The heat from the wick will vaporize the wax which reacts with the oxygen in the air. The two products of the reaction are water and carbon dioxide. In an ideal situation all the wax burns up and complete combustion takes place

2] Incomplete Combustion

Incomplete combustion takes place when the air is in limited supply. And as opposed to complete combustion it is otherwise known as dirty combustion. Due to lack of oxygen, the fuel will not react completely. This, in turn, produces carbon monoxide and soot instead of carbon dioxide.

An example is burning of paper. It leaves behind ash (a form of soot) as a byproduct. In a complete combustion, the only products are water and carbon dioxide. Also, incomplete combustion produces less energy than complete combustion.

3] Rapid Combustion

Another type of combustion is Rapid Combustion. Rapid energy needs external heat energy for the reaction to occur. The combustion produces a large amount of heat and light energy and does so rapidly. The combustion will carry on as long as the fuel is available.

An example is when you light a candle. The heat energy is provided when we light the candle with a matchstick. And it will carry on till the wax burns out. Hence it is a rapid combustion

4] Spontaneous Combustion

As the name suggests the combustion occurs spontaneously. This means that it requires no external energy for the combustion to start. It happens due to self-heating. A substance with low-ignition temperatures gets heated and this heat is unable to escape.

The temperature rises above ignition point and in the presence of sufficient oxygen combustion will happen. The reaction of alkali metals with water is an example.

5] Explosive Combustion

Explosive Combustion happens when the reaction occurs very rapidly. The reaction occurs when something ignites to produce heat, light and sound energy, The simple way to describe is it to call it an explosion. Some classic examples are firecrackers or blowing up of dynamite.

Solved Question for You

Q: When sand is poured over some burning material, the fire goes off. It is because:

  1. Ignition temperature is brought down
  2. Air Supply is cut off
  3. Sand is a band conductor of heat
  4. All of the above

Sol: The correct option is “B”. When sand is poured over any burning substance it cuts off the air supply. Without air, combustion cannot occur and so the flames disappear.

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