Which of the following indicates a system undergoing an exothermic reaction?

Which of the following indicates a system undergoing an exothermic reaction?

• A. A decrease in temperature
• B. An increase in temperature
• C. The formation of a precipitate
• D. Formation of gas bubbles

Answer: (B)

An exothermic reaction is defined as a process that releases heat into its surroundings. As a result, when a system undergoes an exothermic reaction, the temperature of the surrounding environment increases because energy in the form of heat is being released. Therefore, an increase in temperature is a clear indicator that an exothermic reaction is occurring. This heat release means that the reactants have more energy compared to the products, allowing the excess energy to be expelled as thermal energy. The other options may arise from various chemical reactions but do not specifically indicate that heat is released. A decrease in temperature would suggest a cooling effect, potentially associated with an endothermic reaction where heat is absorbed rather than released. The formation of a precipitate or gas bubbles can occur in both exothermic and endothermic reactions, so they are not definitive indicators of the nature of the energy flow in the system.

An exothermic reaction is defined as a process that releases heat into its surroundings. As a result, when a system undergoes an exothermic reaction, the temperature of the surrounding environment increases because energy in the form of heat is being released.

Therefore, an increase in temperature is a clear indicator that an exothermic reaction is occurring. This heat release means that the reactants have more energy compared to the products, allowing the excess energy to be expelled as thermal energy.

The other options may arise from various chemical reactions but do not specifically indicate that heat is released. A decrease in temperature would suggest a cooling effect, potentially associated with an endothermic reaction where heat is absorbed rather than released. The formation of a precipitate or gas bubbles can occur in both exothermic and endothermic reactions, so they are not definitive indicators of the nature of the energy flow in the system.