726. How is chlorine gas used to disinfect water at treatment plants? - KM
Chlorine molecules (Cl2) dissolve easily in water, where they react with water molecules to form hypochlorous acid (HOCl), chlorine ions (Cl-) and hydrogen ions (H+). Hypochlorous acid is a weak acid that partially dissociates into hydrogen ions (H+) and hypochlorite ions (OCl-). Studies have shown that it's predominantly the hypochlorous acid molecules and the hypochlorite ions that disable and kill microorganisms. These molecules and ions diffuse onto and into the microorganisms and oxidize important biological components, such as the protein coats of some viruses, key enzymes in many bacteria, and the genetic materials in both bacteria and viruses. — Thanks to J. Symons for pointing out this mechanism to me and providing me with detailed reference materials.