electrochemistry, science dealing with the relationship between electricity and chemical changes. Of principal interest are the reactions that take place between electrodes and the electrolytes in electric and electrolytic cells (see electrolysis), as well as the reactions that take place in an electrolyte as electricity passes through it. The principles of electrochemistry are applied in a variety of ways, e.g., in electroplating and in the generation of electricity by magnetohydrodynamics. See battery; voltaic cell.

Branch of chemistry concerned with the relation between electricity and chemical change. Many spontaneous chemical reactions liberate electrical energy, and some of these reactions are used in batteries and fuel cells to produce electric power. Conversely, electric current can bring about many reactions that do not occur spontaneously. In the process called electrolysis, electrical energy is converted directly into chemical energy, which is stored in the products of the reaction. This process is applied in refining metals, in electroplating, and in producing hydrogen and oxygen from water. Passage of electricity through a gas generally causes chemical changes, a subject that forms a separate branch of electrochemistry. See also oxidation-reduction.

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