Action of chlorine in water is through:
**Core Concept**
Disinfection of water by chlorine involves the formation of hypochlorous acid (HOCl), a potent antimicrobial agent. This process is crucial in preventing waterborne diseases. The oxidation of chlorine leads to the formation of hypochlorous acid, which is responsible for the antimicrobial effects.
**Why the Correct Answer is Right**
The oxidation of chlorine in water leads to the formation of hypochlorous acid (HOCl) through the following reaction: Cl2 + H2O → HOCl + HCl. HOCl is a strong disinfectant that inactivates microorganisms by disrupting their cell membranes and interfering with their metabolic processes. The formation of HOCl is pH-dependent, with higher concentrations of HOCl formed at lower pH levels. This is why chlorine is often added to water at a pH of around 7.5 to 8.5 to optimize its disinfectant properties.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as it does not specify the correct mechanism of action of chlorine in water. Chlorine does not directly inactivate microorganisms by binding to their DNA, as implied by this option.
**Option B:** This option is incorrect as it refers to the use of chlorine in the treatment of skin conditions, which is not relevant to the disinfection of water.
**Option C:** This option is incorrect as it refers to the use of chlorine dioxide, a different disinfectant that has a different mechanism of action.
**Clinical Pearl / High-Yield Fact**
A commonly used formula to calculate the amount of chlorine needed for water disinfection is the "CT" value, which represents the product of the concentration of chlorine (C) and the contact time (T) in minutes.
**Correct Answer: C.**