What happens in an exothermic reaction?

In an exothermic reaction, energy is released to the surroundings, which results in a net decrease in the internal energy of the system. This process is typically accompanied by an increase in temperature of the surrounding environment.

When a reaction is classified as exothermic, it signifies that the reactants possess higher energy compared to the products. As the reaction proceeds, some of this energy is released, often in the form of heat, light, or sound, contributing to the energy transfer to the surroundings. This release of energy is what makes these reactions important in various applications, such as combustion and respiration in biological systems.

In contrast, the other choices don't accurately reflect the characteristics of exothermic reactions. For instance, in an endothermic reaction, energy is absorbed from the surroundings, which would describe the opposite behavior. Saying that no energy change occurs is misleading since exothermic reactions are defined specifically by the release of energy. Finally, while the temperature of the surroundings generally increases during an exothermic reaction, the reaction itself could involve various temperature changes depending on specific conditions, making that statement too general. Thus, the notion that energy is released to the surroundings perfectly encapsulates the essence of an exothermic reaction.