Types of Chemical Reactions

Chemical reactions are reactions which involve making and breaking of bonds between atom to yield new substances.

    1.    Combination Reaction:

These are the reactions in which one single product is formed from two or more reactants.

Example: i. Formation of Calcium Hydroxide.

CaO (s)(quick lime) + H₂O (l) ----> Ca(OH)₂ (aq)(slaked lime)

ii. Burning of Coal.

C (s) + O₂ (g) ----> CO₂ (g)

iii. Formation of Water.

2H₂ (g) + O₂ (g) ----> 2H₂O (l)

    2.    Displacement Reaction:

These are the reactions in which highly reactive metal displaces less reactive metal from their solution.

Example: i. Fe (s) + CuSO₄ (aq)(copper sulphate) ----> FeSO₄ (aq)(iron sulphate) + Cu (s)

 ii. Zn (s) + CuSO₄ (aq)(copper sulphate) ------> ZnSO₄ (aq)(zinc sulphate) + Cu (s)

iii. Pb (s) + CuCl₂ (aq)(copper chloride) ------> PbCl₂ (aq)(lead chloride) + Cu (s)

    3.    Double Displacement Reaction:

These are the reactions in which exchange of ions between reactants occur.

Example: Na­₂SO₄ (aq)(sodium sulphate) + BaCl₂ (aq)(barium chloride) -----> BaSO₄ (s)(barium sulphate) + 2NaCl (aq)(sodium chloride)

    4.    Oxidation and Reduction Reaction:

1.1.        Oxidation:

These are the reactions in which a substance loses hydrogen or gain oxygen.

          Example: 2Cu + O₂ + Heat ---------> 2CuO

1.2.        Reduction:

These are the reactions in which a substance gain hydrogen or loses oxygen.

          Example: CuO + H₂ + Heat -------> Cu + H₂O

1.3.        Redox Reaction:

These are the reactions in which one reactant gets reduced while other reactant gets oxidized. This type of reaction is also known as Oxidation-Reduction Reaction or Redox Reaction.

Example:

i.                   CuO + H₂ + Heat ------> Cu + H₂O

In above reaction-

                   H₂ ------> H₂O (oxidation)

                   CuO -----> Cu (reduction)

ii.                ZnO + C ------>  Zn + CO

iii.             MnO₂ + 4HCl ------> MnCl₂ + 2H₂O + Cl₂

Observable Effect of Oxidation Reduction in Everyday Life:

1.    Corrosion:

   Attack on metals by moisture, acids, oxygen etc., which corrode metals is called corrosion.

Example: Rusting of Iron, Black coating on Silver, Green coating on Copper.

2.    Rancidity:

   Change in taste and smell of food material prepared by using fat or oil, because fat or oil get oxidized and become rancid.

Endothermic Reaction:

                                      These are the reactions in which heat is absorbed during reaction.

Example: NH₄Cl (s) + H₂O (l) + Heat -                    -------> NH₄Cl (aq)

Exothermic Reaction:

                                      These are the reactions in which heat is evolved during reaction.

Example: CH₄ (g) + 2O₂ (g) -----> CO₂ (g) + 2H₂O (g) + Heat

Precipitation Reaction:

                                      These are the reactions in which insoluble substance called precipitate is obtained when reaction completes, is known as precipitation reaction.

Example: Na₂SO₄ (aq) + BaCl₂ (aq) ----> BaSO₄ (s) + 2NaCl (aq)

 

 

Chemical Reactions Quiz

1. Chemical Reaction, 2H₂O → 2H₂ + O₂ is a-

Synthesis Reaction
Decomposition Reaction
Combustion Reaction
Single Displacement Reaction
Double Displacement Reaction