What are the primary products formed when chlorine reacts with water?

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Multiple Choice

What are the primary products formed when chlorine reacts with water?

Explanation:
When chlorine is added to water, it undergoes hydrolysis and forms hypochlorous acid and hydrochloric acid. The reaction is Cl2 + H2O → HOCl + HCl, so the primary products are HOCl, the active disinfectant, and HCl, the accompanying acid. This explains why chlorine’s effectiveness as a disinfectant depends on the water’s pH, since HOCl is more prevalent at lower pH. The other options don’t come from the simple reaction of chlorine with water. Chlorine dioxide isn’t produced just by dissolving chlorine in water; it requires a different chemical process. Sodium hypochlorite is made by reacting chlorine with sodium hydroxide, not with water alone. Chlorous acid would involve a different oxidation state and reagents, not the immediate hydrolysis product.

When chlorine is added to water, it undergoes hydrolysis and forms hypochlorous acid and hydrochloric acid. The reaction is Cl2 + H2O → HOCl + HCl, so the primary products are HOCl, the active disinfectant, and HCl, the accompanying acid. This explains why chlorine’s effectiveness as a disinfectant depends on the water’s pH, since HOCl is more prevalent at lower pH.

The other options don’t come from the simple reaction of chlorine with water. Chlorine dioxide isn’t produced just by dissolving chlorine in water; it requires a different chemical process. Sodium hypochlorite is made by reacting chlorine with sodium hydroxide, not with water alone. Chlorous acid would involve a different oxidation state and reagents, not the immediate hydrolysis product.

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