Explain the term activation energy of a reaction with a suitable diagram.

Activation energy (Ea): The amount of energy which is to be gained by the reacting species in their normal energy state by collisions to cross over the threshold energy barrier is called activation energy of the reaction.
Activation energy (Ea) = Threshold energy – average energy of the normal molecules.
Endothermic reaction


E_R is energy of reactants
E_p is energy of products
E_T is Threshold energy
E_a = Activation energy of reactants = E_T – E_R
${\mathrm{E}}_{\mathrm{a}}^1$ = Activation energy of products = E_T – E_p