The water in a swimming pool can be kept free from harmful bacteria by adding aqueous sodium chlorate(I), $\text{NaOCl}$. This then reacts with water to form $\text{HOCl}$ molecules that kill bacteria. $\text{OCl}^-(aq) + \text{H}_2\text{O} \rightleftharpoons \text{OH}^-(aq) + \text{HOCl}(aq)$ Under strong sunlight, the $\text{OCl}^-$ ion is decomposed by ultra-violet light. $\text{OCl}^-(aq) + \text{UV light} \rightarrow \text{Cl}^-(aq) + \tfrac{1}{2}\text{O}_2(g)$ Which method would keep the concentration of $\text{HOCl}(aq)$ at the highest level?
- Aacidify the pool water
- Badd a solution of chloride ions
- Cadd a solution of hydroxide ions
- Dbubble air through the water