Chlorine

Following are a few of the important compounds of chlorine.

Calcium hypochlorite, CaOCl: A white powder known as bleaching powder and used for bleaching and as a swimming pool disinfectant. Both its bleaching and its disinfectant qualities come from its chemical instability: it decomposes to release chlorine gas.

Chlorates: Chlorates are compounds of metals with the anion ClO⁻₃. An example is potassium chlorate, KClO₃. Chlorates can cause explosions when mixed with flammable materials, because the chlorate ion decomposes under heat to release oxygen, and the oxygen speeds up the combustion process to explosive levels. Potassium chlorate is used in fireworks.

Chlorides: Chlorides are the salts of hydrochloric acid, HCl. They are compounds of a metal with chlorine and nothing else. Some common examples are sodium chloride (NaCl), ammonium chloride (NH₄Cl), calcium chloride (CaCl₂), and magnesium chloride (MgCl₂). When dissolved in water, these salts produce chloride ions, Cl^-. Polyvinyl chloride, the widely used plastic known as PVC, is a polymer of the organic chloride, vinyl chloride.

Freons are hydrocarbons with fluorine and chlorine atoms substituted for some of the hydrogen atoms in their molecules. They have been widely used as the liquids in refrigerating machines and as propellants in aerosol spray cans. They have been implicated in destroying the ozone layer in the upper atmosphere, however, and their use is now severely restricted.