What is combination reaction

If you want to know what is combination reaction, then here is a complete explanation. We will explore some basics, types, and examples of combination reactions.

Combination reaction definition

A reaction in which two or more reactants react to form a single product is called a combination reaction.

In this reaction, elements or compounds react to form one compound.

 

Combination reaction is also known as synthesis reactions or addition reaction.

 

Combination reaction example

`N_2 + 3H_2 → 2NH_3`

`2Mg + O_2    → 2MgO`

`2H_2 + O_2 → 2H_2O`

`C + O_2 → CO_2`

`CaO + H_2O  → Ca(OH)_2`

 

 

Mostly, combination reactions are exothermic reactions because during the reaction new bonds are formed and a large amount of energy is released but sometimes, they are endothermic in the beginning.

 

`CaO + H_2O → Ca(OH)_2`

The above reaction is a combination reaction in which lime reacts with water to produce slaked lime. A large amount of heat is also produced in the above reaction so it is an exothermic reaction.

`N_2 + 3H_2 → 2NH_3`

 

The above reaction is also a combination reaction in which nitrogen and hydrogen combine to form ammonia gas. In the beginning, it needs a spark to start but once the reaction proceeds, it produces heat, so it is exothermic

Types of combination reaction

We have already discussed that in combination reactions, two or more reactants combine to form a single substance(complex compound), so on the basis of reactants we can classify a combination reaction into the following three types

    

    1.  Element- element combination reaction

    2.  Element -compound combination reaction

    3.  Compound- compound combination reaction

 

    1.   Element-element combination reaction: - In this combination reaction two or more elements combine to form a single compound.

          2Mg + O2    → 2MgO

         In this reaction, two elements – Magnesium and oxygen combine to form single compound magnesium oxide.

   2.  Element -compound combination reaction: - In this combination reaction an element combines with a compound to form a single compound.

 

          `2SO_2 + O_2 → 2SO_3`

          In the above reaction, a compound sulphur dioxide(`SO_2`) combines with an element (oxygen) to form a single compound sulphur trioxide(`SO_3`).

   3.  Compound-compound combination reaction: - In this combination reaction two or more compounds combine to form a single compound.

        `CaO + H_2O → Ca(OH)_2`

        In this reaction, two compounds named lime (CaO)and water(`H_2O`) combine to form a single compound slaked lime(`Ca(OH)_2`)

 

    Related Topics

1. What happens during a chemical reaction

FAQs

   1.  Why combination reactions are exothermic?

Ans. – During combination reactions, two reactants combine and a large amount of heat is produced so these reactions are exothermic reactions.

   2.  Are combination reactions exothermic or endothermic?

Ans. – Mostly combination reactions are exothermic reactions, sometimes they may be endothermic.

   

    3.  How many types of combination reactions?

Ans.-  Combination reactions are of three types depending upon reactants participating in the reaction.

    4.  What are examples of combination reactions in daily life?

Ans.- Formation of water, and ammonia. table salt is the main example of combination reactions in our daily life.