Which disinfectant is typically formed when ammonia is added to chlorine for water treatment?

When ammonia is added to chlorine during water treatment, chloramines are formed. Chloramines are a group of chemical compounds that contain nitrogen and chlorine, and they are commonly used as a secondary disinfectant in drinking water systems. The reaction between chlorine and ammonia results in chloramines, such as monochloramine, dichloramine, and trichloramine, with monochloramine being the most prevalent in water treatment processes.

Chloramines are favored in some water treatment applications because they provide persistent disinfection, reduce the formation of harmful by-products compared to using chlorine alone, and can help in maintaining water quality throughout distribution systems. This makes them particularly useful in reducing the potential for pathogen regrowth and controlling taste and odor issues in the final water supply.

The other substances listed, such as trihalomethanes, are actually by-products that can form when organic matter reacts with chlorine during disinfection, while hypochlorous acid is a strong disinfectant that forms when chlorine is added to water without ammonia. Hydrochloric acid is a strong acid resulting from the dissociation of hydrochloric acid (HCl) and is not relevant to the disinfection process in the same context as chloramines. Thus, the formation of chloramines through