III.

Industrial Applications

Electrolytic decomposition is the basis for a number of important extractive and manufacturing processes in modern industry. Caustic soda, an important chemical in the manufacture of paper, rayon, and photographic film, is produced by the electrolysis of a solution of common salt in water (see Alkalies). The reaction produces chlorine and sodium. The sodium in turn reacts with the water in the cell to yield caustic soda. The chlorine evolved is used in pulp and paper manufacture.

An important industrial use of electrolysis is in the electrolytic furnace, which is employed in the manufacture of aluminum, magnesium, and sodium. In this furnace the resistance of a charge of metallic salts is used to heat the charge until it becomes molten and ionizes. The metal is then deposited electrolytically. See Electric Furnace.

Electrolytic methods are also employed in the refining of lead, tin, copper, gold, and silver. The advantage of extracting or refining metals by electrolytic processes is that the deposited metal is of great purity. Electroplating, another industrial application of electrolytic deposition, is used to deposit films of precious metals on base metals and to deposit metals and alloys, as strengthening or wear-resistant coating, on metal parts. Recent advances in electrochemistry include the development of new techniques for placing layers of material on electrodes to increase their efficiency and endurance. Electrodes made out of polymers are now also possible, through the discovery of polymers that can conduct electricity.