Complete and Incomplete Combustion

Originally oxidation reactions were identified as the reactions where in oxygen gas participates. There, oxygen combines with another molecule, to produce an oxide. In this reaction, oxygen undergoes reduction and the other substance undergoes oxidation. So basically oxidation reaction is adding oxygen to another substance. For example, in the following reaction, hydrogen undergoes oxidation and, therefore, oxygen atom has been added to hydrogen, forming water.

2H₂ + O₂ -> 2H₂O

Another way to describe oxidation is as loss of hydrogen. There are some occasions where it is hard to describe oxidation as adding oxygen. For example, in the following reaction, oxygen has added to both carbon and hydrogen, but only carbon has undergone oxidation. In this instance, oxidation can be described by saying it is the loss of hydrogen. As hydrogens have removed from methane when producing carbon dioxide, carbon there has been oxidized.

CH₄ + 2O₂ -> CO₂ + 2H₂O

There are various types of oxidation reactions. Some are happening in the natural environment daily. For example, the cellular respiration, which produces energy inside every living organism’s cells, is also an oxidation reaction. Most of the elements are combining with atmospheric oxygen and form oxides. Mineral formation, metal rusting are results of this. Other than the natural phenomenon, there are man -involved oxidizing reactions too. Burning and combustion are some oxidizing reactions where humans are involved.

Complete Combustion

Combustion or heating is a reaction where heat is produced by an exothermic reaction. Combustion is an oxidation reaction. For the reaction to take place, a fuel and an oxidant should be there. Substances undergoing the combustion are known as fuels. These can be hydrocarbons like petrol, diesel, methane, or hydrogen gas, etc. Usually the oxidizing agent is oxygen, but there can be other oxidants like fluorine too.

In the reaction, the fuel is oxidized by the oxidant. So this is an oxidation reaction. When hydrocarbon fuels are used, the products after a complete combustion are usually carbon dioxide and water. In a complete combustion, few products will be formed, and it will produce the maximum energy output that the reactant can give. However, for a complete combustion to take place, unlimited and constant oxygen supply and optimum temperature should be there.  Hence, complete combustion is not always favored.

Incomplete Combustion

When there isn’t enough oxygen, incomplete combustion takes place. If the combustion had not happened completely, carbon monoxide and other particles can be released into the atmosphere and which can cause a lot of pollution.

What is the difference between Complete Combustion and Incomplete Combustion? • Complete combustion takes place when there is a constant and enough oxygen supply. Incomplete combustion takes place when there isn’t enough oxygen supply. • In complete combustion, limited number of products is produced in contrast to incomplete combustion. • If a hydrocarbon undergoes complete combustion, only carbon dioxide and water is produced. If it undergoes incomplete combustion, carbon monoxide and carbon particles may also be produced. • Incomplete combustion cause environmental pollution. • Complete combustion results in more energy than incomplete combustion.