• NEET
      • Class 11th
      • Class 12th
      • Class 12th Plus
    • JEE
      • Class 11th
      • Class 12th
      • Class 12th Plus
    • Class 6-10
      • Class 6th
      • Class 7th
      • Class 8th
      • Class 9th
      • Class 10th
    • View All Options
      • Online Courses
      • Offline Courses
      • Distance Learning
      • Hindi Medium Courses
      • International Olympiad
    • NEET
      • Class 11th
      • Class 12th
      • Class 12th Plus
    • JEE (Main+Advanced)
      • Class 11th
      • Class 12th
      • Class 12th Plus
    • JEE Main
      • Class 11th
      • Class 12th
      • Class 12th Plus
  • NEW
    • JEE MAIN 2025
    • NEET
      • 2024
      • 2023
      • 2022
    • Class 6-10
    • JEE Main
      • Previous Year Papers
      • Sample Papers
      • Result
      • Analysis
      • Syllabus
      • Exam Date
    • JEE Advanced
      • Previous Year Papers
      • Sample Papers
      • Mock Test
      • Result
      • Analysis
      • Syllabus
      • Exam Date
    • NEET
      • Previous Year Papers
      • Sample Papers
      • Mock Test
      • Result
      • Analysis
      • Syllabus
      • Exam Date
    • NCERT Solutions
      • Class 6
      • Class 7
      • Class 8
      • Class 9
      • Class 10
      • Class 11
      • Class 12
    • CBSE
      • Notes
      • Sample Papers
      • Question Papers
    • Olympiad
      • NSO
      • IMO
      • NMTC
    • TALLENTEX
    • AOSAT
    • ALLEN e-Store
    • ALLEN for Schools
    • About ALLEN
    • Blogs
    • News
    • Careers
    • Request a call back
    • Book home demo
NCERT SolutionsCBSE NotesCBSE Exam
Home
Science
Types of Chemical Reactions

Types of Chemical Reactions

Accordingly, the reactions are classified in different types.

Types of chemical reactions

1.0Combination Reaction

The reactions in which two or more substances combine to form a single new substance are called combination reactions.

Some more examples of combination reactions  

(a) Between element - element

(i) Burning of Coal

C(s) +  O2(g) ⎯→ CO2(g)

Carbon    Oxygen          Carbon dioxide 

(ii) Formation of Water 

2H2(g)       +                   O2(g)  ⎯→ 2H2O()

Hydrogen Oxygen Water

(iii) Burning of Magnesium in air 

2Mg(s) + O2(g) ⎯→ 2MgO(s)

Magnesium Oxygen Magnesium oxide

(iv) Formation of Iron sulphide

Fe(s) + S(s) ⎯→ FeS(s)

Iron Sulphur                 Iron sulphide


(b) Between compound - compound

(v) Formation of Ammonium chloride

NH3(g)     + HCl(g) ⎯→ NH4Cl(s)

Ammonia Hydrogen Ammonium

Chloride Chloride

(vi) Formation of Calcium Carbonate 

CaO(s) + CO2(g)   ⎯→ CaCO3(s)

Calcium oxide Carbon Calcium

(Quick lime) dioxide carbonate 


(c) Between compound- element

(vii) Reaction of carbon monoxide with oxygen

2CO(g) + O2 (g)  ⎯→ 2CO2(g)

This is also an exothermic reaction.

(viii) 2NO(g) + O2(g) ⎯→ 2NO2(g)

2.0Decomposition Reaction

The reaction in which a single compound breaks up into two or more simpler substances is known as decomposition reaction. The decomposition reaction generally takes place when energy in some form such as heat, electricity or light is supplied to the reactants.

Types of Decomposition Reaction 

(a) Thermal decomposition: The reaction in which a single compound breaks up into two or more simpler substances by the action of heat is called thermal decomposition reaction.

(b) Electric Decomposition: The reaction in which a single compound breaks up into two or more simpler substances by the action of electricity is called electric decomposition reaction. 

(c) Photo decomposition: The reaction in which a single compound breaks up into two or more simpler substances by the action of light is called photo decomposition reaction.

Note: Photolysis of AgBr is used in black and white photography.

Decomposition Reaction

3.0Displacement Reactions

A reaction in which a more reactive element displaces a less reactive element from its compounds is called displacement reaction. The elements involved may be metals or non-metals.

Relative reactivity of metals

Different metals possess different reactivities. The arrangement of metals in a vertical column in order of their decreasing reactivity from top to bottom is called reactivity series or activity series of metals.

Note : A suggested way of remembering reactivity series

Relative Reactivity of Metals

Relative reactivity of some non-metals

Among halogens, fluorine is most reactive, and iodine is least reactive.

F2 > Cl2 > Br2 > I2

Some more examples of displacement reactions.

(i)Zn(s) + CuSO4 (aq) ⎯→ ZnSO4(aq) + Cu(s)

     Zinc           Copper sulphate         Zinc sulphate   Copper

(Bluish-Silver) (Blue)     (Colourless)   (Reddish Brown)

(ii) Cu(s) +    2AgNO3(aq)  ⎯→ Cu(NO3)2(aq)  + 2Ag(s)

      Copper           Silver nitrate Copper nitrate     Silver 

                  (Dark blue)

4.0Double Displacement Reactions 

Those reactions in which two different atoms or groups of atoms are exchanged are called double displacement reactions or double decomposition reactions or metathesis reactions. 

5.0Oxidation and Reduction Reactions

The reaction which involves addition of oxygen or removal of hydrogen from a substance is called oxidation reaction.

The reaction which involves addition of hydrogen or removal of oxygen from a substance is called reduction reaction. 

Note : According to the electronic concept, Oxidation Is Loss of electrons. Reduction Is Gain of electrons.

Memory map

Memory map

6.0 Also Read

What is Air Pollution?

Solution And Its Components

Treatment of Water 

Oxygen

Colloidal Solution

Separation of The Gases of The Air

Benzoyl Peroxide

Separating The Components of A Mixture

Corrosion

Table of Contents


  • 1.0Combination Reaction
  • 2.0Decomposition Reaction
  • 2.1Types of Decomposition Reaction 
  • 3.0Displacement Reactions
  • 4.0Double Displacement Reactions 
  • 5.0Oxidation and Reduction Reactions
  • 6.0 Also Read

Frequently Asked Questions

A solution of slaked lime produced by the reaction above is used for white washing of walls. Calcium hydroxide reacts slowly with the carbon dioxide in the air to form a thin layer of calcium carbonate on the walls. Calcium carbonate is formed after two to three days of white washing and gives a shiny finish to the walls.

When barium hydroxide is added to ammonium chloride, an endothermic reaction takes place. Since heat is absorbed, the bottom of the test tube becomes cold.

Two different atoms or groups of atoms are exchanged between reactants.

Oxidation involves the addition of oxygen or removal of hydrogen (or loss of electrons). Reduction involves the addition of hydrogen or removal of oxygen (or gain of electrons).

Join ALLEN!

(Session 2025 - 26)


Choose class
Choose your goal
Preferred Mode
Choose State
  • About
    • About us
    • Blog
    • News
    • MyExam EduBlogs
    • Privacy policy
    • Public notice
    • Careers
    • Dhoni Inspires NEET Aspirants
    • Dhoni Inspires JEE Aspirants
  • Help & Support
    • Refund policy
    • Transfer policy
    • Terms & Conditions
    • Contact us
  • Popular goals
    • NEET Coaching
    • JEE Coaching
    • 6th to 10th
  • Courses
    • Online Courses
    • Distance Learning
    • Online Test Series
    • International Olympiads Online Course
    • NEET Test Series
    • JEE Test Series
    • JEE Main Test Series
  • Centers
    • Kota
    • Bangalore
    • Indore
    • Delhi
    • More centres
  • Exam information
    • JEE Main
    • JEE Advanced
    • NEET UG
    • CBSE
    • NCERT Solutions
    • NEET Mock Test
    • Olympiad
    • NEET 2025 Answer Key
    • JEE Advanced 2025 Answerkey
    • JEE Advanced Rank Predictor

ALLEN Career Institute Pvt. Ltd. © All Rights Reserved.

ISO