Calcium hypochlorite [Ca(OCl)2] is used as a disinfectant for swimming pools. When dissolved in water it produces hypochlorous acid
Ca(OCl)2(s) + 2H2O(l) → 2HClO(aq) + Ca(OH)2(s)
which ionizes as follows:
HClO(aq) → H+(aq) + ClO-(aq) Ka 5 3.0 3 1028
As strong oxidizing agents, both HClO and ClO- can kill bacteria by destroying their cellular components. However, too high a HClO concentration is irritating to the eyes of swimmers and too high a concentration of ClO2 will cause the ions to decompose in sunlight. The recommended pH for pool water is 7.8. Calculate the percent of these species present at this pH.