What is meant by the activation energy of a reaction? - Leaving Cert Chemistry - Question i - 2016

The activation energy of a reaction refers to the minimum combined energy required for colliding particles—such as molecules, atoms, or ions—to react and form products. Essentially, it is the energy barrier that must be overcome for a reaction to take place.

This energy is pertinent in the context of effective collisions, where not only must particles collide, but they must also possess a sufficient amount of energy to surpass this threshold. Without meeting this energy requirement, the reaction cannot proceed, highlighting the importance of activation energy in chemical kinetics.