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Decomposition Reaction Definition

The process of breakdown of any physical or chemical entity is referred to as decomposition. Chemical decomposition results from breaking down a complex chemical entity into one, two, or more components.

Decomposition Types

1. Physical Decomposition or Changes

Physical changes are typically reversible. However, they can also be irreversible and only affect the physical characteristics. A substance's physical characteristics modify when it goes through a physical change. For example, breaking glass.

2. Chemical Decomposition or Changes

Chemical changes are permanent transformations in which new products are created. The reactant and product are different entity and has completely distinct characteristics. Chemical equations are a simple way of representing a chemical reaction. Chemical equations act as a symbolic representation of the chemical reaction.

Decomposition Reaction Definition

Decomposition Reaction

A decomposition reaction is a chemical process in which one reactant splits into more than 1 item. Most of the time, the decomposition reactions need energy. One of its main uses is the extraction of metals from ores.

Decomposition Reactions Types

1. Thermal Decomposition

It is a decomposition in which a single reactant is split into several products with heat. For thermal decomposition processes, high temperatures are required.

For e.g.:

CaCO3 → CaO + CO2

2. Photo Decomposition

This decomposition reaction uses light or photons to split the reactants into several products. The reactant's bonds are broken by utilizing light energy. Photolysis is another name for this reaction.

For e.g.:

2AgCl → 2Ag + CL2

3. Electrolytic Decomposition

Electrolytic decomposition refers to the breakdown of any molecule using electricity. Certain chemicals quickly separate when heated by electricity.

For e.g., Electrolysis of water.

2H2O → 2H2 + O2

Application of Decomposition Reactions

  • In the human body, decomposition reactions aid in food digestion.
  • A decomposition reaction is used while making cement and gypsum.
  • Metals are extracted from their oxides and chlorides by using decomposition reactions.
  • In the welding procedure, this reaction is used.

Double Decomposition Reaction

In a double decomposition reaction, two reactants exchange negative and positive ions to create two new molecules.

For example,

HCl(aq) + NaOH(aq) →NaCl(aq) + H2 O (l)


  • Acidic hydrochloric is HCl.
  • A sodium hydroxide base is NaOH.
  • Sodium chloride is known as NaCl.
  • Water is H2 O .

FAQs on Decomposition Reaction

1. Difference between combination reaction and decomposition reaction


Decomposition Reaction Combination Reaction
1. One reactant splits into two or more products in a decomposition reaction. 1. Combination reaction often occurs when two or more atoms or compounds combine to create one product.
2. Decomposition reactions are typically represented as QP → Q + P. 2. Combination reactions are typically represented as Q + P → QP.
3. Example., 2AgCl → 2Ag + CL2 3. Example., 2Ag + CL2 → 2AgCl
4. Uses of the decomposition reaction:

  • Cement or calcium oxide formation.
  • Provides indigestion relief.
  • Elimination of metals from oxides.
4. Uses of combination reaction:

  • For drinking water, it is utilized.
  • Marble stones and chalk pieces are made from calcium carbonate.

2. Are all decomposition processes endothermic in nature?


Yes, practically all decomposition processes require heat to break down; as a result, they are endothermic in nature.

3. Differentiate between endothermic and exothermic reactions.


Endothermic reactions Exothermic reactions
1. It is the chemical process that takes in thermal energy from the surroundings. 1. Exothermic reactions are those in which heat energy is released into the environment.
2. Heat energy is needed for the process. 2. Energy can be emitted as sound, light, heat, or electricity.
3. Due to the absorption of heat, enthalpy is positive. 3. Due to the evolution of heat, enthalpy is negative.
4. For example, cooking, evaporation, ice melting, gas molecules, and photosynthesis. 4. For example, chemical bonds, etc.

4. Is decomposition a chemical or physical process?


The chemical compound splits into tiny particles during decomposition. Thus, it is a chemical process instead of a physical one.

5. List the main applications of the decomposition reaction.


Some significant applications of the decomposition reaction include the following:

  1. The metal is frequently extracted using the decomposition process.
  2. Manufacturing processes for cement and gypsum require a decomposition reaction.
  3. This process helps the stomach to digest food.

6. List examples of endothermic processes.


  1. The process of cooking an egg
  2. Ion pair separation
  3. A melting ice cube
  4. Melting of granular salts
  5. Baking bread
  6. Vaporizing liquid water
  7. Transforming ice into water vapor
  8. Cooking an egg
  9. Melting solid salts

7. What are the applications of endothermic reactions?


Here are a few applications for it:

1. Photosynthesis

Unlike mammals (including humans), trees make their food. Photosynthesis is the procedure by which trees generate food, which is thought to result from an endothermic reaction.

Photosynthesis involves sunlight absorption through leaves and producing food when mixed with water and carbon dioxide.

2. Sublimation

The process of sublimation is another illustration of an endothermic reaction. In sublimation, a substance can move from the solid to the gaseous. For e.g., dry ice, dry ice is simply solid carbon dioxide. A molecule directly transitions from a liquid to a gas state in evaporation.

3. Cooking food

An endothermic reaction occurs during the cooking of food. Let's imagine that you are making noodles. The noodles take in the heat from the pan as it cooks.

8. What are the applications of decomposition reactions?


Here are a few applications for it:

1) Fertiliser Production

By utilizing the decomposition reaction, fertilizers are produced. Nitrogen gas ( ) and water are produced when ammonium nitrate decomposes. Trees utilize nitrogen gas for growth, and water aids in photosynthesis.

2) Food Preserving

Nitric oxide and nitrogen dioxide are produced during the decomposition of sodium nitrite ( , which works as a preservative in meat products.

3) Pollutant Removal

Pollutants are removed from the environment using decomposition processes.

8. Differentiate thermal decomposition and thermal dissociation


Thermal Decomposition Thermal Dissociation
1. A type of chemical breakdown occurred by heat is referred to as thermal decomposition. 1. The process of ionizing a material using heat is called thermal dissociation.
2. It involves several steps. 2. It is a one-step procedure.

9. What are the similarities between thermal decomposition and thermal dissociation?


A compound can be divided into smaller components utilizing heat energy during thermal decomposition as well as thermal dissociation.

10. What is decomposition?


The procedure of breaking down or condensing any physical or chemical substance.

Decomposition Types

1) Physical Decomposition

Although physical changes are typically reversible, they can also be permanent and only affect the physical properties. A substance's physical qualities alter when it goes through a physical change. For, e.g., breaking glass, etc.

2) Chemical Decomposition

Chemical transformations are permanent transformations in which new products are created.

11) What is the mean by electrolytic decomposition?


  • A single reactant is broken down into several products through the process of electrolytic decomposition, which occurs when electricity is applied.
  • These are the chemical processes that, when heated, break down and generate a range of goods.
  • Formula format : Decomposition Reaction Definition
  • Example: Zinc carbonate breaks down into two after being heated, that is, zinc oxide and carbon dioxide.

12) Explain the reversible reaction


In a reversible reaction, the reactants create products that later combine to return the reactants to their original state. When a reversible reaction reaches equilibrium, the concentrations of the reactants and products stop changing.

NH4 Cl(s) → NH3 (g) + HCl(g)

Next TopicGas Definition

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