An example of reversible reaction is

Reversible reaction occurs in both forward and backward directions. In a chemical reaction, if one of the reactants is solid or precipitation then it is very difficult to occur the reversible reaction. In the decomposition of potassium chlorate both KCl and O₂ are evolved rapidly by heat released. Hence, the backward reaction is not taking place for KClO₃ . In the formation of ammonia, the reactants and products are gases only. Hence, both forward and backward reactions are taking place in a closed vessel.