Why the energy of the product might be lower than the energy of the reactants

A reaction in which heat energy is absorbed is said to be endothermic. You can show this on simple energy diagrams. For an exothermic change: Notice that in an exothermic change, the products have a lower energy than the reactants.

A reaction in which heat energy is absorbed is said to be endothermic. You can show this on simple energy diagrams. For an exothermic change: Notice that in an exothermic change, the products have a lower energy than the reactants.