Types of Combustion: Meaning and Examples

Types of Combustion: The creation of fire was a watershed moment in the history of civilisation. Fire is a source of heat energy that we utilise to cook meals, power vehicles, and operate factories, among other things. When a material burns in the air, it creates heat and light, which is known as fire. In this post, we’ll look at several forms of combustion, or how chemicals burn in the air. Let’s have a look at what combustion is before we get into the different forms of combustion.

Combustion

The process in which a substance chemically combines with oxygen to give off heat and sometimes light also is called combustion. As heat (energy) is evolved during the process, combustion is exothermic in nature.

The substance which burns readily is called a combustible substance. It is also called fuel. For example, petrol, LPG, wax, kerosene, paper, cloth, wood, coal, etc., are some combustible substances or fuels.

The substances which do not burn are called non-combustible substances. For example, water, glass, sand, etc., are some non-combustible substances.

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Conditions Necessary for Combustion

The conditions necessary for combustion are:

i. Presence of a combustible substance
ii. Presence of the supporter of combustion- that is, air or oxygen
iii. Ignition temperature

Types of Combustion

Combustion can be classified into several categories based on the amount of energy required and the reaction’s byproducts. There are five different forms of combustion, which are listed below:

i. Complete Combustion
ii. Incomplete Combustion
iii. Rapid Combustion
iv. Spontaneous Combustion
v. Explosion

Complete Combustion

This type of combustion occurs when there is an unlimited supply of air or oxygen. An exothermic reaction occurs between the carbon and hydrogen atoms of a hydrocarbon fuel with oxygen. The hydrocarbon will burn completely and leave only two byproducts- carbon dioxide and water.

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An example of complete combustion is the burning of a candle- The heat evaporates the wax from the wick, which combines with the oxygen in the air. Water and carbon dioxide are the two byproducts of the process. In an ideal case, all of the wax is consumed, and combustion is complete.

Incomplete Combustion

This type of combustion takes place when there is a limited supply of air or oxygen. There is still water produced, but there is also carbon monoxide and carbon. As compared to complete combustion, less energy is emitted in this reaction.

Below given is the image that shows incomplete combustion in factories-

An example of incomplete combustion can be seen during the burning of propane in a limited supply of oxygen.

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Soot

Carbon is emitted in the form of fine black particles. This can be seen as smoky flames, which are deposited as soot. Soot can irritate the lungs. It darkens the interiors of buildings and has the potential to clog boilers and other appliances and start a fire.

Carbon monoxide

Carbon monoxide is a highly poisonous gas. It enters the bloodstream through the lungs and binds to haemoglobin in red blood cells. This decreases the blood’s oxygen-carrying capacity, causes drowsiness to those exposed to it, and may even cause death.

Rapid Combustion

Combustion in which a substance burns rapidly and produces heat and flame is known as rapid combustion. This is usually attained by introducing external heat. It is also known as fast combustion. Substances that undergo rapid combustion have lower ignition temperatures—for example, combustion of LPG, CNG, petrol, etc.

Spontaneous Combustion

When a substance suddenly starts turning into a flame without the supply of any external cause such as heating is called spontaneous combustion. Substances that have relatively low ignition temperature generally burn by spontaneous combustion.

Some examples of spontaneous combustion are as follows:

i. Phosphorus and sulphur start burning instantaneously at room temperature.
ii. Haystacks, linseed oil, coal, pyrite, etc., sometimes start burning suddenly with flame because of the increase in temperature.
iii. In coal mines, fire breaks out many times because of the combustion of coal dust (leading to the death of many workers).
iv. Fire often breaks out suddenly in forests because of an increase in temperature due to the sun.

Explosion

When combustion is accompanied by sudden production of heat, sound and a large amount of gas, it is called an explosion. This type of combustion occurs at an extremely rapid pace. Firecrackers and bombs undergo an explosion. The fireworks burst when a spark ignites the fuse, producing heat, light, and sound.

Summary

Combustion is a chemical reaction that occurs when fuel (hydrocarbon) and oxygen come into contact. When fuel and oxygen react, heat and light energy are released. The flame is made up of heat and light energy. As a result, the Combustion reaction’s formula is Hydrobcarbon + Oxygen = Heat energy. Combustion is employed in automobile engines, rocket engines, and a variety of other machines. Combustion may be classified into five main categories.

In this article, we studied that burning anything in the presence of air or oxygen is combustion. We also studied that there are five types of combustion depending on the energy and byproducts. Now we know in detail the types and examples of various types of combustion.

Frequently Asked Questions (FAQs) on Types of Combustion

Q.1. Respiration is a type of combustion. Give a reason.
Ans: Combustion is a process in which things are burned in the presence of air to produce carbon dioxide, water vapour and energy.
Respiration is a process in which the food products are burned slowly at a low temperature to produce carbon dioxide, energy, and water, making it similar to combustion.
Thus, both combustion and respiration provide energy and produce the same byproducts.

Q.2. How many types of combustion are there?
Ans:  Combustion can be classified into several categories based on the amount of energy required and the reaction’s byproducts. There are five different forms of combustion- complete combustion, incomplete combustion, rapid combustion, spontaneous combustion, and explosion.

Q.3. Which type of combustion occurs by self-heating?
Ans: The combustion that occurs by self-heating is spontaneous combustion.
Substances that have relatively low ignition temperature undergo such a type of combustion. For example, haystacks, linseed oil, coal, pyrite, etc., sometimes start burning suddenly with flame because of the increase in temperature.

Q.4. What is the difference between complete and incomplete combustion?
Ans: The difference between complete and incomplete combustion is as follows:

Q.5. What are the disadvantages of incomplete combustion?
Ans: The disadvantages of incomplete combustion are as follows:
i. Incomplete combustion of a fuel produces a poisonous gas, carbon monoxide and unburnt carbon particles, which are harmful to humans and the environment.
ii. It produces less heat which leads to the wastage of fuel.

Q.6. What type of reaction is combustion?
Ans: The process in which a substance burns in the presence of air/ oxygen to produce energy is called combustion. As heat (energy) is evolved during the process, combustion is exothermic in nature.

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