Using the reactions O+H2 → OH+H to explore the importance of the atomic quantum states on chemical kinetics and reaction dynamics

The O + H2 reaction is a particular example to alert the importance of a clear definition of the quantum state of an atom when referring to a chemical reaction. In its ground state, O (3P), the oxygen atom reacts with H2 through an energy barrier with small rate constant. In contrast, when the oxygen atom is in its first excited state, O (1D), the reaction O + H2 occurs without energy barrier and the rate constant is seven orders of magnitude higher. The dynamic behaviour of this reaction depends also on the quantum state of the oxygen atom