What is formed when water combines with chlorine in the chlorine feed system?

When water combines with chlorine in the chlorine feed system, hydrochloric acid is formed. This reaction occurs when chlorine gas is introduced to water, resulting in a dissociation that produces both hydrochloric acid and hypochlorous acid. The overall reaction can be summarized as chlorination leading to the formation of hypochlorous acid (which is effective for disinfection) and hydrochloric acid, which can influence pH levels in the water.

The other options refer to different chemical processes or reactions that do not directly relate to the scenario presented. Sodium chloride is typically produced when chlorine reacts with sodium, not just with water. Chlorine dioxide is a specific compound that can be generated through different chemical reactions involving chlorine but doesn't occur directly from chlorine and water. Chlorinated water refers to water that has been treated with chlorine for disinfection purposes, but it is not a specific product of the reaction taking place. In this context, hydrochloric acid is the accurate chemical product formed from the direct combination of water and chlorine in the feed system.