Potassium metabisulphite, is a white crystalline powder with a pungent sulfur odour. The main use for the chemical is as an antioxidant or chemical sterilant. It is a sulfite and is chemically very similar to sodium metabisulfite, with which it is sometimes used interchangeably.
Sodium metabisulphite is an inorganic compound of chemical formula Na2s2o5. The name is sometimes referred to as disodium (metabisulfite, etc. ). It is used as a disinfectant, antioxidant and preservative agent.