When free Cl2 is added to water, which acid is stronger?

The correct answer is Hydrochlorous Acid (HClO), which is produced when chlorine (Cl2) is dissolved in water, leading to the formation of hypochlorous acid. Hydrochlorous acid is a weak acid, but it is considered stronger than other acids present in the options due to its ability to dissociate and release hydrogen ions (H+) more effectively under typical conditions encountered in water treatment processes.

Hydrochlorous acid is a commonly utilized disinfectant in water treatment because of its effectiveness in killing bacteria and other pathogens. This reaction emphasizes its potential for producing stronger acidic conditions compared to the other options listed.

Hydrochloric Acid (HCl) is indeed a strong acid, but it does not form when free chlorine is added to water and is not directly related to chlorine disinfection processes. Chlorous Acid is generated through different chemical processes and is generally weaker than hydrochlorous acid in terms of dissociation. Lastly, Carbonic Acid, a product of CO2 saturated in water, is also weaker compared to hydrochlorous acid in terms of generating hydrogen ions and its effectiveness in disinfection scenarios.

In summary, Hydrochlorous Acid stands out as the stronger acid in the context of chlorine addition to water, primarily due to its