Question

Define reversible and irreversible reactions. Give examples.

Answer 1

Reversible reaction:-

Reactions in which the reactants are converted to products and products are converted back to reactants are called reversible reactions.

A reversible reaction has two parts :-

1. Forward reaction:- The reaction in which the reactants are converted to products is called a forward reaction.
2. Backward reaction:- The reaction in which the products are converted back to reactants is called backward reaction.

Example of reversible reaction:-

$N2\left(g\right)+3H_2\left(g\right)\rightleftharpoons 2N{H}_3\left(g\right)$

Irreversible reaction:-

Reactions in which the reactants are converted to products but the products that cannot be converted back to reactants are called irreversible reactions.

Examples of irreversible reactions:-$4Fe\left(S\right)+3O_2\left(g\right)\to 2F{e}_2{O}_3\left(s\right)$

Comparative study of reversible and irreversible reactions:-

Reversible reactions	Irreversible reactions
Can take place in both directions	Can take place in one direction only
Equilibrium is established	No equilibrium is established
Can be made irreversible under some conditions	Cannot be made reversible under any conditions
Represented by two half-arrows in opposite directions (⇌)	Represented by a full arrow pointing towards the products (→)

Reversible reactions are those which proceed in both directions but irreversible reactions are those which proceed in one direction only.