Sodium thiosulphate anhydrous
| Chemical formula | Na2O3S2 |
| Density | 1.67 g/cm3 |
| Molar mass | 158.11 g/mol |
| CAS number | 7772-98-7 |
| EC index number | 231-867-5 |
| HS Code | 28323000 |
| Storage | without limitation |
| SDS | available |
| Odour | odourless |
| Form | solid |
| Color | colourless |
| p H value | 6.0 – 8.5(50 g/l 20 °C ) |
| Solubility in water | 701 g/l ( 20 °C ) |
| Thermal decomposition | >300 °C |
| Assay | ≥ | 97 | % |
| Description | Conforms | ||
| Solubility | Conforms | ||
| Identification | Conforms | ||
| Appearance of solution | Conforms | ||
| pH | 6.0 – 8.5 | ||
| Sulphide | ≤ | 0.002 | % |
| Heavy metals | ≤ | 0.005 | % |
| Iron | ≤ | 0.005 | % |
Sodium thiosulphate anhydrous is a white, crystalline inorganic compound commonly used as a reducing agent and in analytical chemistry. It is valued for its ability to neutralize oxidizing agents and is widely applied in laboratories and pharmaceutical contexts.
🏭⚗️ Production
Sodium thiosulphate anhydrous is typically produced by reacting sodium sulfite with sulfur in aqueous solution, followed by crystallization and drying to remove water, yielding the anhydrous salt.
🔬 Properties
The chemical formula is Na₂S₂O₃ with a molar mass of approximately 158.11 g/mol. It appears as a white crystalline powder, highly soluble in water but insoluble in alcohol. It is stable under normal conditions but decomposes upon heating, releasing sulfur oxides.
🧪 Applications
In laboratories, sodium thiosulphate anhydrous is used as a titrant in iodometric titrations, photographic fixing agent, and to neutralize chlorine in water treatment. In pharmaceutical applications, it serves as an antidote for cyanide poisoning and as a reducing agent in certain formulations.
⚠️ Safety
Sodium thiosulphate anhydrous is generally considered safe with low toxicity but may cause mild irritation to eyes and skin upon contact. Standard laboratory protective equipment such as gloves and goggles should be used. It should be stored in a cool, dry place away from strong acids and oxidizers.
