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 t ohandle. 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.