At any given temperature, there is a wide distribution of kinetic energies in reactant molecules. When the temperature of reactions is increased the number of reactant molecules having sufficient energy to pass over the barrier also increases, leading to increased reaction speedAt any given temperature, there is a wide distribution of kinetic energies in reactant molecules. When the temperature of reactions is increased, the number of reactant molecules having sufficient energy to pass over the barrier also increases, leading to increased reaction speed