Explain the use of chlorine in water treatment.

In the subtopic Halide ions and uses of chlorine, this AQA A-Level Chemistry 7405 learning objective focuses on explain the use of chlorine in water treatment. It belongs to Group 7(17), the halogens, so revision should stay anchored to this exact subtopic rather than drifting into a generic GCSE-level chemistry summary. Approved keywords to use include chlorine, water treatment. Water treatment. means the process of making water safe for drinking and other uses, often involving the addition of chlorine Avoid the mistake of students often confuse the role of chlorine in water treatment as solely a disinfectant, neglecting its role in oxidation and the formation of chlorinated compounds; instead, chlorine acts as a strong oxidizing agent in water treatment. When chlorine is added to water, it reacts to form hypochlorous acid (HOCl), which kills bacteria and other pathogens. The reaction can be summarized as: Cl2 + H2O ⇌ HOCl + HCl. This shows that chlorine not only disinfects but also contributes to the formation of chlorinated by-products For exam answers, explain how chlorine is used to disinfect water by killing bacteria and other pathogens