Reactive oxygen atoms are produced during the chlorination of water. This process involves the addition of chlorine gas (Cl2) to water (H2O) to disinfect it and kill harmful bacteria and microorganisms. The reaction is as follows:

Cl2 + H2O -> HCl + HClO

In this reaction, chlorine gas reacts with water to form hydrochloric acid (HCl) and hypochlorous acid (HClO). It is the hypochlorous acid that produces reactive oxygen atoms.

Explanation:

1. Chlorine gas (Cl2):
Chlorine gas is introduced into water to kill bacteria and microorganisms. It is a powerful disinfectant and reacts with water to form hydrochloric acid and hypochlorous acid.

2. Water (H2O):
Water is the medium in which the chlorination process takes place. It is the reactant that reacts with chlorine gas to form hydrochloric acid and hypochlorous acid.

3. Hydrochloric acid (HCl):
Hydrochloric acid is formed during the reaction between chlorine gas and water. It is a strong acid and has disinfectant properties. However, it does not produce reactive oxygen atoms.

4. Hypochlorous acid (HClO):
Hypochlorous acid is the primary product of the chlorination reaction. It is a weak acid and has powerful disinfectant properties. It is also responsible for producing reactive oxygen atoms.

5. Reactive oxygen atoms:
Hypochlorous acid (HClO) can undergo a process called disassociation, where it breaks down into reactive oxygen atoms. These reactive oxygen atoms are highly reactive and can attack and destroy organic matter, including bacteria and microorganisms.

In conclusion, during the chlorination of water, reactive oxygen atoms are produced by the disassociation of hypochlorous acid (HClO), which is formed when chlorine gas reacts with water. These reactive oxygen atoms play a crucial role in disinfecting water and killing harmful bacteria and microorganisms.