Redox pairs and redox potential
Oxidation and reduction applied to water treatment - General principles

In fact, the reactions and are equilibria, liable, depending on the conditions of the medium, to shift to the left or to the right. In both cases, electron transfer takes place between an oxidant (respectively Fe ³⁺ or O ₂ ) and a conjugate reductant (respectively Fe ²⁺ or H ₂ O) according to the general formula :

i.e. :