Sodium metabisulfite is a white or yellow crystalline powder or small crystal with a strong SO2 odor, the specific gravity is 1.4, soluble in water, and the aqueous solution is acidic. When it is in contact with a strong acid, it releases SO2 to form a corresponding salt.

Specification
Appearance :White or slightly yellow crystalline powder or small crystal
Solid content :?97%
So2 :?65%
Water insoluble matter :?0.05%
PH value :4-4.8
Iron(Fe):?0.002%