Understanding Exothermic Reactions

Thermodynamics is a branch of physical science that deals with the relationships between heat and other forms of energy. One of the key concepts in thermodynamics is the law of conservation of energy, which states that energy cannot be created or destroyed in an isolated system.

In a chemical reaction, if the total energy of the products is lower than that of the reactants, the reaction is said to be exothermic, releasing energy to the surroundings. Conversely, if the total energy of the products is higher than that of the reactants, the reaction is classified as endothermic, absorbing energy from the surroundings. Consider a simple reaction where substance A reacts with substance B to form products C and D. Which statement below correctly describes the energy change in this reaction?