What is the chemical name of free chlorine commonly referred to?

The chemical name of free chlorine is commonly referred to as the hypochlorite ion. This is because free chlorine is mainly found in water systems in the form of hypochlorous acid (HOCl) and its dissociated form, the hypochlorite ion (OCl-). Free chlorine is often used as a disinfectant in water treatment processes to kill bacteria and other pathogens. The presence of hypochlorite ions in the water is essential for effective chlorination, as they are the active species that contribute to the disinfecting action.

Sodium chloride, while related to chlorine due to its composition (NaCl), is simply table salt and does not refer to the active disinfectant property of chlorine in water systems. Chloramine is a compound formed from the reaction of ammonia and chlorine, and it serves a different purpose in water treatment, acting as a secondary disinfectant. Calcium hypochlorite is a solid form of chlorine used for disinfection, but it is a compound containing hypochlorite rather than being free chlorine itself. Thus, the hypochlorite ion is the most accurate term when discussing free chlorine in the context of water treatment practices.