in a chemical change how does the total energy of the reactants compare to the total energy of the products

All chemical changes requires a substantial amount of energy. Depending on the type of reaction, the energy of reactants and products differs.

In an exothermic chemical change where heat is always given off to the surroundings, the energy of the product is less than that of reactants.

For endothermic changes, the surrounding becomes colder at the end of the reaction. This implies that the heat energy of the product is higher than that of the reactants.