Which statement correctly describes activation energy?

Which statement correctly describes activation energy?

• A. The energy barrier that must be overcome by particles to react.
• B. The energy released during the reaction.
• C. The energy required to break all bonds in both reactants.
• D. The energy difference between products and catalysts.

Answer: (A)

Activation energy is the minimum energy that reacting particles must have to get a reaction started. It represents the energy barrier on the reaction pathway that must be overcome to reach the activated complex and form products. If particles don’t have enough energy, they can collide and bounce off without reacting; if they do have enough energy, they can reach the transition state and the reaction proceeds. This barrier explains why higher temperature speeds up reactions—more particles have energy equal to or above that barrier. It also explains why catalysts speed things up by providing an alternative route with a lower barrier. The activation energy is not the energy released when products form (that’s the overall energy change of the reaction), nor is it simply the energy to break every bond in the reactants. It’s specifically the energy barrier that must be overcome to start the reaction.

Activation energy is the minimum energy that reacting particles must have to get a reaction started. It represents the energy barrier on the reaction pathway that must be overcome to reach the activated complex and form products. If particles don’t have enough energy, they can collide and bounce off without reacting; if they do have enough energy, they can reach the transition state and the reaction proceeds. This barrier explains why higher temperature speeds up reactions—more particles have energy equal to or above that barrier. It also explains why catalysts speed things up by providing an alternative route with a lower barrier. The activation energy is not the energy released when products form (that’s the overall energy change of the reaction), nor is it simply the energy to break every bond in the reactants. It’s specifically the energy barrier that must be overcome to start the reaction.