Sodium Thiosulfate
Disodium Thiosulfate, Sodium Hyposulfite
- CAS
- 7772-98-7
- EC
- 231-867-5
- Sectors
- Water & Wastewater Treatment, Mining & Metals, Pharma & Healthcare
Sodium Thiosulfate (CAS 7772-98-7) is an inorganic thiosulfate salt supplied as a white powder, typically used as a photographic fixer, a dechlorination agent in water treatment, a reagent in gold mining, a medical antidote for cyanide, and in textile processing. Density 1.67 g/cm³, melting point 48°C (pentahydrate); highly soluble in water, hygroscopic. Produced by boiling sodium sulfite with sulfur.
Typical Properties
| Molecular formula | H2O3S2.2Na |
|---|---|
| Molecular weight | 158.11 g/mol |
| Appearance | White powder |
| Form | Solid |
| Color | White |
| Melting point | 48 °C |
| Boiling point | 100 °C |
| Density | 1.667 g/cm³ |
| Water solubility | Soluble in water. Insoluble in alcohol. |
| pH | 6.0-8.5 (25°C, 50mg/mL in H2O) |
| HS code | 28323000 |
| Grades available | Technical Grade |
Typical literature values for identification; lot-specific results are stated on the certificate of analysis (COA) and the safety data sheet (SDS) that accompany every delivery.
Sodium Thiosulfate
Applications
Used in photography as fixer, water treatment for dechlorination, gold mining, medical antidote for cyanide, and textiles.
Safety & Risks
Low toxicity but irritates eyes, skin; releases toxic gases in fire. Avoid oxidizers; use PPE.
Packaging
In 25kg bags or drums; rinse triply for recycling or reconditioning.