ABSTRACT
In all true compounds of oxygen, the element has an oxidation number of -2 except in the oxygen fluorides, where the oxygen may be assigned an oxidation number of +2 because of the higher electronegativity of the F- ion. The oxygen-water couple is highly irreversible and it is virtually impossible to obtain equilibrium in systems involving this couple. Since the oxygen overvoltage is very high on most metal anodes and is both strongly and nonlinearly dependent on the current density, it is difficult to predict the behavior of a given system from tables of standard electrode potentials alone. For the electrochemical evolution of oxygen from aqueous electrolytes at metal anodes, the reaction is not homogeneous but occurs on the anode surface between adsorbed reactants and intermediates. An interesting feature of the oxidizing action of ozone is the fact that only one of the oxygen atoms is reduced while the other two atoms form molecular oxygen.
