Characteristic

 

Sodium metabisulfite or sodium pyrosulfite (IUPAC spelling; Br. E. sodium metabisulphite or sodium pyrosulphite) is an inorganic compound of chemical formula Na₂S₂O₅. The substance is sometimes referred to as disodium metabisulfite.

Chemical formula:Na₂S₂O₅, Na-O-(S=O)-O-(S=O)-O-Na

Molar mass: 190.107 g/mol

Appearance: White to yellow powder

Odor: Faint SO₂

Density: 1.48 g/cm³

Melting point: 170 °C (338 °F; 443 K) decomposition begins at 150 °C

Solubility in water:45.1 g/100 mL (0 °C);65.3 g/100 mL (20 °C);81.7 g 100 mL (100 °C)

Solubility: Very soluble in glycerol;Slightly soluble in ethanol

 

Application

 

Sodium metabisulfite is used as an active ingredient in campden tablets, as a cleaning agent for potable water reverse osmosis membranes, as a preservative and an antioxidant in food. It also acts as a corrosion inhibitor in oil and gas industry, as a bleaching agent in the production of coconut cream, as the source of sulfur dioxide and in the destruction of cyanide in commercial gold cyanidation processes. It is utilized in the precipitation of gold from auric acid as well as in the waste water treatment to remove hexavaent chromium as trivalent chromium by precipitation after reduction. Further, it is used in photography. In addition, it plays as an oxygen scavenger to eliminate the dissolved oxygen in wastewater and in pipes.