Notes On Types of Redox Reactions - CBSE Class 11 Chemistry

Based on the nature of the reaction, redox reactions are divided into four types. They are combination reactions, decomposition reactions, displacement reactions and disproportionation reactions.

A combination reaction is a chemical reaction in which two or more substances combine to form a single new substance. A combination reaction is said to be a redox reaction if either one (or) both the reactants should be in elemental state.

Ex:

A decomposition reaction is a chemical reaction in which a compound breaks up into two or more simple substances. Decomposition reaction is the opposite of combination reaction. Not all redox reactions are decomposition reactions.

A decomposition reaction is said to be a redox reaction if at least one of the products of the decomposition reaction is in the elemental state.

 

Ex:

In a displacement reaction the atom (or) ion in a compound is replaced by the atom (or) ion of some other element or compound.

Displacement Reactions
   → Metal Displacement Reactions
   → Non-Metal Displacement Reactions

In a metal displacement reaction the metal in a compound is displaced by some other metal in the elemental state.

Ex:

CuSO4(aq) + Zn(s) → Cu(s) + ZnSO4(aq)

In a non-metal displacement reaction a metal (or) a non-metal displaces another non-metal in a compound.

Ex:

A disproportionation reaction is a reaction in which the same element is oxidised as well as reduced. Such reactions occur when one of the reacting elements exists in at least three oxidation states.

Ex:

Summary

Based on the nature of the reaction, redox reactions are divided into four types. They are combination reactions, decomposition reactions, displacement reactions and disproportionation reactions.

A combination reaction is a chemical reaction in which two or more substances combine to form a single new substance. A combination reaction is said to be a redox reaction if either one (or) both the reactants should be in elemental state.

Ex:

A decomposition reaction is a chemical reaction in which a compound breaks up into two or more simple substances. Decomposition reaction is the opposite of combination reaction. Not all redox reactions are decomposition reactions.

A decomposition reaction is said to be a redox reaction if at least one of the products of the decomposition reaction is in the elemental state.

 

Ex:

In a displacement reaction the atom (or) ion in a compound is replaced by the atom (or) ion of some other element or compound.

Displacement Reactions
   → Metal Displacement Reactions
   → Non-Metal Displacement Reactions

In a metal displacement reaction the metal in a compound is displaced by some other metal in the elemental state.

Ex:

CuSO4(aq) + Zn(s) → Cu(s) + ZnSO4(aq)

In a non-metal displacement reaction a metal (or) a non-metal displaces another non-metal in a compound.

Ex:

A disproportionation reaction is a reaction in which the same element is oxidised as well as reduced. Such reactions occur when one of the reacting elements exists in at least three oxidation states.

Ex:

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