What is the primary product formed when chlorine is added to water?

When chlorine is added to water, the primary product formed is hypochlorous acid (HOCl). This reaction occurs because chlorine (Cl2) reacts with water (H2O) to produce both hypochlorous acid and hydrochloric acid (HCl) in a process known as chlorination. However, hypochlorous acid is the dominant product and is a weak acid that plays a critical role in disinfection and sanitation processes. HOCl is an effective antimicrobial agent, making it essential in water treatment facilities to eliminate pathogens.

While hydrochloric acid is also formed during this reaction, it is not the primary focus for disinfection purposes. Ozone and chlorine gas are not directly produced when chlorine is added to water in this context, as ozone is a different substance used separately for water treatment, and chlorine gas is what is initially introduced before the reaction occurs. Thus, the formation of hypochlorous acid is significant in ensuring safe and clean water by effectively killing bacteria and viruses.