Sodium metabisulfite (Na2S2O5) is an inorganic compound with a white or yellow crystal appearance and a strong pungent odor. Soluble in water, the aqueous solution is acidic, and contact with strong acids releases sulfur dioxide and generates the corresponding salts. In the air for a long time, it is oxidized into sodium sulfate, so sodium metabisulfite can not be long.

Melting point: >170 °C (starting at 150 °C)

Water solubility: soluble (54 g/100 ml)

Density: 1.48g /cm3

Molecular weight :190.09   

Appearance: White to light yellow crystals with pungent odor

CAS number :7681-57-4  

Use: Antioxidant

EINECS number :231-673-0   

Cautionary terms R: R22, R31, R41