Calcium hypochlorite (CaOCl)
When chlorine gas is dissolved into a solution of calcium oxide (CaO) and sodium hydroxide(NaOH), calcium hypochlorite is produced.
Essentially made up of the calcium salts of hypochlorous acid, calcium hypochlorite is a white, solid substance that is available either in tablet or granular powder form. While this compound is extremely corrosive and requires proper handling,it is very stable and may be stored for a long period of time before actual use. It also gives off a strong, distinct chlorine odor.
Adding calcium hypochlorite to water produces hypochlorite and calcium ions. Water treatment using this chlorine form requires a lesser concentration than that of chlorine gas.
Sodium hypochlorite (NaOCl)
Dissolving chlorine gas into a sodium hydroxide solution produces sodium hypochlorite.Composed of the sodium salts of hypochlorous acid, sodium hypochlorite comes in liquid form. It is clear with a light yellow color, and like mostchlorine-containing substances, has a strong characteristic smell.
In treating water using sodium hypochlorite, the recommended amount is approximately 0.2 to2 mg of NaOCl per liter of water, a dosage that is much less first two forms of chlorine. Compared to the other forms of chlorine, NaOCl is also easier to handle. On the other hand, it is the earliest to decompose, and therefore cannot be stored for more than a month. A cool, dark, and dry place is best for storage.