Which of the following diagrams best represents the potential energy changes during an exothermic reaction?

• A. Reactants and products have the same potential energy, with no energy change.
• B. Reactants start at a higher potential energy than products, with energy released to the surroundings.
• C. Reactants start at a lower potential energy than products, with energy absorbed from the surroundings.
• D. Reactants start at a higher potential energy than products, with energy absorbed from the surroundings.

Answer: (B)

Verified step by step guidance

1. Understand that an exothermic reaction releases energy to the surroundings, meaning the system loses energy during the reaction.
2. Recall that potential energy diagrams plot the potential energy of reactants and products on the y-axis against the reaction progress on the x-axis.
3. In an exothermic reaction, the reactants have higher potential energy than the products because energy is released as the reaction proceeds.
4. Therefore, the diagram should show a downward slope from reactants to products, indicating a decrease in potential energy and release of energy to the surroundings.
5. Eliminate options where reactants and products have the same potential energy or where products have lower potential energy but energy is absorbed, as these do not represent exothermic reactions.