Introduction:
In chemical reactions, the energy required to initiate the reaction is known as the energy of activation. It is the minimum amount of energy that the reactants must possess in order to undergo a chemical reaction. Exothermic reactions release energy in the form of heat, and in such reactions, the energy of activation of the reactants is less than the energy of activation of the products.

Explanation:
To understand why the energy of activation of the reactants is less than the energy of activation of the products in an exothermic reaction, let's consider the reaction profile diagram.

Reaction Profile Diagram:
A reaction profile diagram shows the energy changes that occur during a chemical reaction. It consists of an energy axis (y-axis) and the reaction progress (x-axis). The energy of the reactants is shown on the left side of the diagram, while the energy of the products is shown on the right side.

Key Points:
1. Energy of Activation of Reactants: The energy of activation of the reactants is the energy required to break the bonds in the reactant molecules and convert them into an unstable transition state. This energy is shown as the peak on the reaction profile diagram.
2. Energy of Activation of Products: The energy of activation of the products is the energy required to break the bonds in the transition state and convert it into the stable product molecules. This energy is also shown as a peak on the reaction profile diagram.
3. Exothermic Reaction: In an exothermic reaction, the energy released during the formation of new bonds in the products is greater than the energy required to break the bonds in the reactants. As a result, the overall energy change is negative, and the reaction releases heat.
4. Difference in Activation Energies: Since exothermic reactions release energy, the energy of activation of the products is higher than the energy of activation of the reactants. This is because the products have a lower energy level than the reactants, and it requires more energy to convert the transition state into stable products.

Conclusion:
In conclusion, the energy of activation of the reactants in an exothermic reaction is less than the energy of activation of the products. This is because exothermic reactions release energy, and the products have a lower energy level than the reactants. The energy of activation represents the minimum energy required to initiate a chemical reaction, and in exothermic reactions, this energy is lower for the reactants compared to the products.