Which gas is produced when chlorine is mixed with organic matter in water?

When chlorine is mixed with organic matter in water, chloramine is produced as a result of the chemical reactions taking place. Chloramines are formed when chlorine reacts with ammonia, which can be present in organic matter as nitrogen-containing compounds. This reaction is significant in water treatment processes, particularly in the disinfection phase, as chloramines can provide longer-lasting disinfection compared to chlorine alone.

Chloramine formation is relevant in the context of water treatment because it helps minimize the formation of harmful byproducts that can occur with free chlorine, such as trihalomethanes (THMs), which can be a concern for water quality and safety. Additionally, chloramines tend to have a lower corrosive potential than chlorine gas, making them preferable in certain applications, especially in systems with older pipes or sensitive equipment.

The other options represent different substances or reactions that do not directly result from the mixing of chlorine with organic matter in water. Understanding the formation of chloramines helps water operators manage water quality effectively.