Oxidizing Agents If one reagent in a reaction contributes oxygen, extracts hydrogen, or extracts electrons, it is said to be an oxidizing agent. Of course, it is reduced in the process. Since oxidation and reduction are symmetric processes, always occurring together, there is always an oxidizing agent and a reducing agent in the reaction. Since both are always present, why bother with this terminology? If oxidation of some substance is the desired end, then it is useful to find an agent which will readily accomplish the oxidation. Useful oxidizing agents are bleaches and antiseptics. Not so useful is the action of oxygen in the air in the corrosion of metals by oxidation. The relative strengths of oxidizing agents can be inferred from their standard electrode potentials. The strongest oxidizing agents are shown from the standard electrode table. Cathode (Reduction) Half-Reaction Standard Potential E° (volts) MnO4-(aq) + 8H+(aq) + 5e- -> Mn2+(aq) + 4H2O(l) 1.49 H2O2(aq) + 2H+(aq) + 2e- -> 2H2O(l) 1.78 Co3+(aq) + e- -> Co2+(aq) 1.82 S2O82-(aq) + 2e- -> 2SO42-(aq) 2.01 O3(g) + 2H+(aq) + 2e- -> O2(g) + H2O(l) 2.07 F2(g) + 2e- -> 2F-(aq) 2.87 Fluorine, having the largest positive value of electrode potential, is the strongest oxidizing agent.