Final answer:
In the given exothermic reaction AB + CD -> AD + BC, energy is released as heat due to the conversion of higher stored energy in the reactants to lower energy in the products, supporting the law of conservation of energy.
Step-by-step explanation:
If the chemical reaction AB + CD -> AD + BC releases heat, the stored energy of the reactants is higher than the stored energy of the products. This is because heat is a product of this reaction, signifying that energy is leaving the system, making this an exothermic reaction. Consequently, the correct answer to whether energy is absorbed or released during the reaction is that energy is released.
Through the process of this chemical reaction, part of the potential chemical energy stored in the molecular bonds of the reactants is converted into thermal energy. This energy transfer manifests as heat, which is observed with a temperature rise in the surroundings.
To summarize the principles involved: when a chemical reaction is exothermic, it results in the net release of heat as the reactants' stored potential energy is reduced and converted into kinetic energy, in this case, thermal energy. This aligns with the law of conservation of energy, which states that energy in a closed system is neither created nor destroyed, but rather transformed from one form to another.