Which of the following best describes what happens during an exothermic reaction?

• A. No energy change occurs between the system and the surroundings.
• B. Energy is released to the surroundings, usually in the form of heat.
• C. Energy is absorbed from the surroundings, causing the temperature to decrease.
• D. The products have higher enthalpy than the reactants.

Answer: (B)

Verified step by step guidance

1. Understand the definition of an exothermic reaction: it is a chemical reaction that releases energy to the surroundings.
2. Recall that energy released during an exothermic reaction is often in the form of heat, which can increase the temperature of the surroundings.
3. Recognize that in an exothermic reaction, the enthalpy of the products is lower than that of the reactants because energy is given off.
4. Contrast this with an endothermic reaction, where energy is absorbed from the surroundings and the products have higher enthalpy than the reactants.
5. Conclude that the best description of an exothermic reaction is that energy is released to the surroundings, usually as heat.