On an energy profile diagram for an exothermic reaction
- A. the products lie at a lower energy level than the reactants
- B. the products lie above the reactants
- C. there is no activation energy barrier
- D. the activation energy is always zero
Explanation
An exothermic reaction releases energy to the surroundings, so the products sit lower and the enthalpy change is negative, but the curve still rises to a peak first because the activation barrier must be crossed. Confusing the barrier height with the overall enthalpy change is the classic error when reading these diagrams. An endothermic profile has the products higher than the reactants.