All energetically effective collisions do not result in a chemical change. Explain with the help of an example.

Explanation

According to collision theory, the reaction rate generally depends upon two factors. These are energy and orientation factor. Sometimes, we come across certain reactions which are highly exothermic and are energetically favoured. This means that the reactants have sufficient activation energy to make the collisions effective. However, they still do not proceed at a given temperature. This is attributed to the reason that the reactant molecules are not properly oriented at the time of collisions. This means that the atoms of reactant molecules which actually combine to form the products are not facing each other.