BRINE ELECTROLYSIS

"Electrolysis of an aqueous solution of common table salt (sodium chloride), also called ""brine,"" results in the production of chlorine gas at the anode and hydrogen gas at the cathode. Since the hydrogen is produced by breaking up water molecules, the solution is becoming basic around the cathode and a solution of sodium hydroxide (also called ""caustic"" or ""alkali"") is produced. If the electrolysis is carried out in a divided cell, the products are chlorine, caustic, and hydrogen. If the electrolysis is carried out in an undivided cell and the chlorine gas and the caustic are allowed to mix and react with each other, sodium hypochlorite (bleach) is produced if the cell operates close to room temperature, and sodium chlorate is produced if the cell is operated near the boiling point of water. Electrolysis is the only large-scale industrial process for the production of chlorine gas and these chlorine chemicals. Smaller scale cells are also used to produce chlorine-based disinfectants in municipal water-treatment plants and for swimming pools. See also an Encyclopedia Article. "