ELECTROCHEMICAL REACTION

"An oxidation/reduction reaction that occurs in an electrochemical cell. The essential feature is that the simultaneously occurring oxidation-reduction reactions are spatially separated. E.g., in a spontaneous ""chemical reaction"" during the oxidation of hydrogen by oxygen to water, electrons are passed directly from the hydrogen to the oxygen. In contrast, in the spontaneous electrochemical reaction in a galvanic cell two separate electrode reactions occur. The hydrogen is oxidized at the anode by transferring electrons to the anode and the oxygen is reduced at the cathode by accepting electrons from the cathode. The overall electrochemical reaction is the sum of the two electrode reactions. The ions produced in the electrode reactions, in this case positive hydrogen ions and the negative hydroxyl (OH-) ions will recombine in the solution to form the final product of the reaction: water. During this process the electrons are carried from the anode to the cathode through an outside electrical circuit where the electronic current can drive a motor, light a light bulb, etc. The reaction can also be reversed, water can be decomposed into hydrogen and oxygen by the application of electrical power in an electrolytic cell. "