Sodium Hydrosulfite
Sodium Sulfhydrate
Sodium hydrosulfite, also known as sodium dithionite or sodium hypodisulfite, is a white to grayish crystalline powder with formula Na2S2O4 and molecular weight 174.11 g/mol. It has a density of 2.38 g/cm³, decomposes above 90°C, and emits a faint sulfurous odor. Highly soluble in water (up to 182 g/L at 20°C) but insoluble in alcohols; unstable in air, oxidizing to sodium bisulfate. Acts as a powerful reducing agent, produced from zinc and SO2 or formate reduction.
Sodium Hydrosulfite
Key in textile dyeing for reducing vat dyes like indigo; in paper bleaching for pulp whitening; water treatment for deoxygenation; organic synthesis, photography, and as a quencher in biochemistry.
Spontaneously combustible in moist air; reacts with water or acids to release toxic SO2. Irritates skin, eyes, and respiratory system. Store dry and cool; UN1384, Hazard Class 4.2; use PPE.
In 50kg iron or fiber drums with PE liners to exclude moisture. Handle carefully to prevent ignition from friction.
