Activation energy (Ea) is the minimum energy that colliding molecules must possess in order to react and form the activated complex. It represents the energy barrier that must be overcome for a reaction to occur. A higher activation energy means fewer molecules have enough energy to react, so the reaction is slower; a catalyst speeds a reaction by lowering it.

活化能(Ea)是碰撞分子为发生反应、形成活化络合物所必须具备的最低能量。它代表反应发生所必须越过的能垒。活化能越高,具有足够能量发生反应的分子越少,反应越慢;催化剂通过降低活化能来加速反应。