An exothermic reaction profile illustrates the release of energy, with the products possessing lower energy than the reactants.

In an exothermic reaction, the energy level begins at a higher point and ends at a lower point, signifying that energy is released throughout the reaction. This occurs because the energy needed to break the bonds in the reactants is less than the energy released when new bonds are established in the products. The energy difference is emitted, typically as heat, which is why the term “exothermic” is used—it translates to “heat released to the outside.”

The reaction profile is commonly depicted as a graph, where the x-axis represents the progression of the reaction and the y-axis indicates energy levels. The reactants are positioned on the left side of the graph, starting at a higher energy level. As the reaction advances, the energy level drops, reflecting the energy being released. The products are situated on the right side of the graph at a lower energy level.

The apex of the graph denotes the activation energy, which is the minimum energy required to initiate the reaction. In the context of an exothermic reaction, this energy is necessary to break the bonds in the reactants. Once this activation energy is supplied, the reaction can proceed, resulting in the release of energy as the products are formed.

In summary, an exothermic reaction profile serves as a visual representation of the energy changes occurring during a reaction. It clearly indicates that the products have less energy than the reactants, demonstrating that energy has been released. This characteristic is fundamental to exothermic reactions, which are prevalent in various fields of chemistry, including combustion reactions and numerous acid-base reactions.