(iv) For a collision to be effective, the following two barriers are to be cleared,
(a) Energy barrier: “The minimum amount of energy which the colliding molecules must possess as to make the chemical reaction to occur, is known as threshold energy”.
• In the graph ‘E’ corresponds to minimum or threshold energy for effective collision.
• There is an energy barrier for each reaction. The reacting species must be provided with sufficient energy to cross the energy barrier.