In chemistry, to bleach something generally means to whiten it or oxidize it. A bleach is a chemical that can produce these effects. Common chemical bleaches include sodium hypochlorite, or "chlorine bleach," and "oxygen bleach," which contains hydrogen peroxide or a peroxide-releasing compound (eg. sodium perborate, or sodium percarbonate). "Bleaching powder" is calcium hypochlorite. Bleaching can be a preliminary step in the process of dyeing. Bleach"

Calcium hypochlorite is a chemical compound with formula ( )2. It is widely used for water treatment and as a bleaching agent (bleaching powder). This chemical is considered to be relatively stable and has greater available chlorine than sodium hypochlorite (liquid bleach). It is manufactured using Calcium Process and Sodium Process. Calcium hypochlorite is not 100% soluble. For that reason it should preferably be used in soft to middle hard water. There are 2 types of Calcium hypochlorite viz. a dry and a hydrated quality. Latter quality is more safe in handling. For use in swimming pools Calcium hypochlorite can be used in combination with a stabiliser (Cyanuric acid). The stabiliser will prevent loss of chlorine because of UV radiation. Calcium hypochlorite"

(Calcium peroxide) General Calcium peroxide"

Carbamide peroxide, also called urea peroxide, is an oxidising agent, consisting of hydrogen peroxide compounded with urea. The molecular formula is CH6N2O3, or CH4N2O.H2O. It is white crystalline material that releases oxygen in contact with water. Carbamide peroxide"