Which of the following is a true statement about an energy diagram for an exothermic reaction?

• A. The activation energy is negative.
• B. The products have lower energy than the reactants.
• C. The energy diagram shows no energy change between reactants and products.
• D. The reactants have lower energy than the products.

Answer: (B)

Verified step by step guidance

1. Understand that an energy diagram for a chemical reaction plots the potential energy of the system as the reaction progresses from reactants to products.
2. Recall that in an exothermic reaction, energy is released to the surroundings, meaning the products have less energy than the reactants.
3. Recognize that activation energy (Ea) is always a positive value representing the energy barrier that must be overcome for the reaction to proceed; it cannot be negative.
4. Analyze the given statements: since the reaction is exothermic, the energy of the products is lower than that of the reactants, so the energy diagram must show a decrease in energy from reactants to products.
5. Conclude that the true statement is: 'The products have lower energy than the reactants,' because this correctly describes the energy change in an exothermic reaction.