What is the term for the curve depicting potential energy versus reaction progress?

• A. Energy diagram
• B. Reaction intermediate
• C. Endothermic
• D. Exothermic

Answer: (A)

An energy diagram is the curve that shows potential energy as the reaction progresses from reactants to products. It visually captures how energy rises to the activation energy at the transition state and then falls to the energy level of the products. This type of diagram also lets you see the overall energy change: if the products end up at a lower energy than the reactants, the process is exothermic; if higher, it’s endothermic. A reaction intermediate would be a valley along the curve representing a short-lived species, not the entire curve itself. Endothermic and exothermic describe the direction of energy change, not the name of the diagram.