What is decomposition reaction?

Here you will find a complete answer to what is a decomposition reaction. In this article, you will learn definitions, types, and examples of decomposition reactions.

Decomposition Reaction Definition

That reaction is called a decomposition reaction in which one compound changes into two or more simpler substances.

Energy in the form of heat, light, or electricity is required in the decomposition of a substance.

Decompose means ‘To break down'.

Examples of Decomposition reaction

1. `FeSO_4. 5H_2O\overset{\Delta }{\rightarrow}FeSO_4 + 5H_2O`

2.`CaCO_3\overset{\Delta }{\rightarrow}CaO + CO_2`

3. `FeSO_4\overset{\Delta }{\rightarrow}Fe_2O_3 + SO_2 + SO_3`

4. `KClO_3\overset{\Delta }{\rightarrow}2KCl + 3O_2`

5. `2PbNO_3\overset{\Delta }{\rightarrow}2PbO + 4NO_2 + O_2`

6. `AgCl\overset{\light}{\rightarrow}2Ag+ Cl_2`

 7. `2H_2O\overset{\text (electricity)} {\rightarrow}2H_2 + O_2`

So, we can easily understand through the above examples a complex compound gets broken down into two or more simpler substances.

Types of Decomposition Reaction

A complex substance is broken down when it gets energy from surroundings, so on the basis of energy absorbed, the decomposition reaction is of following three types

    1.  Thermal decomposition

    2.  Electrolytic decomposition

    3.  Photolytic decomposition

     1.  Thermal decomposition reaction: - The reaction in which heat energy is given to the substance and it breaks down into two or simpler substances is called thermal decomposition reaction.

`CaCO_3\overset{\Delta }{\rightarrow}CaO + CO_2`

In the above reaction, calcium carbonate(`CaCO_3`) is heated which causes decomposition into calcium oxide and carbon dioxide. Decomposition occurs due to the presence of heat so it is thermal decomposition.

   2.  Electrolytic decomposition: - The reaction in which electrical energy is given to the substance and it breaks down into two or simpler substances is called electrolytic decomposition reaction.

`2H_2O\overset{\text (electricity)} {\rightarrow}2H_2 + O_2`

    When an electric current is passed in water, it decomposes into hydrogen and oxygen.

3.  Photolytic decomposition: - The reaction in which light energy is given to the substance and it breaks down into two or simpler substances is called photolytic decomposition reaction.

 `AgBr\overset{\light}{\rightarrow}2Ag+ Br_2`

In the presence of light, silver bromide beaks down into silver and bromine.

 

Uses of Decomposition reaction

In our daily life, we can see different uses of decomposition reactions. Some of them are given below-

i.    Baking soda is used in cooking. Baking soda is added in bread and cake to make them spongy and soft, when it is heated it decomposes to produce CO₂.

ii.   Hydrogen peroxide is used in bleaching and removing stains. When it is exposed to light, it produces oxygen which is used to bleach fabric and remove stains.

iii.   In making medicines

iv.   Compounds present in fertilizers decompose in soil to release nutrients.

Are all decomposition reactions endothermic?

Yes, all decomposition reactions are endothermic. In decomposition, energy (heat) is absorbed by the substance.

For example- thermal decomposition reactions are endothermic reactions.

But sometimes decomposition reactions can be exothermic reactions.

For example- The decomposition of vegetable matter into compost is an example of an exothermic reaction.

Related Topics

1. What happens during a chemical reaction

FAQs

    1.  Are all decomposition reactions exothermic?

Ans. – Most decomposition reactions are endothermic but in some cases, they are endothermic in the beginning but after some time they become exothermic.

 

    2.  What are the different types of decomposition reactions?

Ans.-  Thermal decomposition, photolytic and electrolytic decomposition.

   

    3.  How is energy involved in a decomposition reaction?

Ans.- Energy is absorbed in the form of heat, light, or electricity in decomposition reactions.

   

    4.  Are all decomposition reactions endothermic?

Ans. – Yes, all decomposition reactions are endothermic.

   

    5.  Can a decomposition reaction be exothermic?

Ans.- Most of the decomposition reactions are endothermic but in some cases the decomposition of vegetative parts releases heat.

   

    6.  Can decomposition reactions occur naturally?

Ans. – Yes, decomposition reactions occur in natural conditions, for example – the decomposition of organic waste material.