Which of these statements about chemical reactions is false?

The statement regarding the total mass of products exceeding that of the reactants is false due to the Law of Conservation of Mass, which states that in a closed system, the mass of the reactants must equal the mass of the products. This principle asserts that atoms are neither created nor destroyed in a chemical reaction; they are simply rearranged to form new compounds. Therefore, the total mass before the reaction occurs is equal to the total mass after the reaction.

On the other hand, the other statements are true. Reactions can absorb energy (endothermic reactions) or release energy (exothermic reactions), indicating that reactions can indeed both absorb and release heat. Reactants undergo a change in energy as bonds are broken and formed, leading to either the release or absorption of energy. Specifically, exothermic reactions are defined by their ability to release energy, often in the form of heat, to their surroundings. This understanding affirms the nature of energy changes occurring during chemical reactions.