Which compound is formed when chlorine combines with water?

When chlorine combines with water, it can undergo a reaction that produces both hydrochloric acid and chloramines. The reaction begins with chlorine (Cl2) dissolving in water (H2O) to produce hypochlorous acid (HOCl), which is a weak acid. Under certain conditions, particularly in the presence of ammonia (NH3), hypochlorous acid can further react to form chloramines, such as monochloramine (NH2Cl) or dichloramine (NHCl2).

Hydrochloric acid (HCl) is formed in the reaction when chlorine effectively displaces the hydrogen in water, resulting in a combination with hydroxide ions (OH-) found in the water. Therefore, in the presence of ammonia or certain conditions, the system can generate both hydrochloric acid and chloramines simultaneously.

The presence of both compounds in the reactions highlights the complexity and versatility of chlorine chemistry, especially in disinfection processes within wastewater treatment systems. This indicates the significance of understanding these compounds' formation for effective water treatment practices.