Sodium thiosulfate pentahydrate
CAS 10102-17-7
EC 600-156-5
Formula H2O3S2.5H2O.2Na
MW 248.18 g/mol
Salts & Minerals Water TreatmentPrinting & PackagingTextile, Leather & PaperFood & NutritionPharmaceuticals & Healthcare Preservation & BiocideAntioxidant & StabilizerCatalysis
Description
Sodium thiosulfate pentahydrate (CAS 10102-17-7), commonly known as Hypo or Antichlor, is an inorganic sodium salt supplied as translucent crystals or white powder. It carries no E-code designation and is registered under EC 600-156-5. The formula H2O3S2.5H2O.2Na reflects its stable pentahydrate structure.
In water treatment, it neutralises residual chlorine by reducing hypochlorite to chloride ions, preventing downstream process interference. In photographic and textile processing, it acts as a fixing agent and dechlorinating reducer, breaking halogen bonds to stabilise or clear treated substrates. Pharmaceutical compounders also use it as an antioxidant to protect sensitive formulations from oxidative degradation.
Sodium thiosulfate pentahydrate is available in technical, food-grade (FCC), and pharmaceutical-grade (Ph.Eur.) specifications to meet sector-specific compliance requirements. The substance is registered under REACH and supplied in 25 kg bags or bulk quantities. Buyers should confirm grade suitability against their application and regional regulatory obligations.
In water treatment, it neutralises residual chlorine by reducing hypochlorite to chloride ions, preventing downstream process interference. In photographic and textile processing, it acts as a fixing agent and dechlorinating reducer, breaking halogen bonds to stabilise or clear treated substrates. Pharmaceutical compounders also use it as an antioxidant to protect sensitive formulations from oxidative degradation.
Sodium thiosulfate pentahydrate is available in technical, food-grade (FCC), and pharmaceutical-grade (Ph.Eur.) specifications to meet sector-specific compliance requirements. The substance is registered under REACH and supplied in 25 kg bags or bulk quantities. Buyers should confirm grade suitability against their application and regional regulatory obligations.
Physical Properties
| Melting Point | 48.5 °C |
| Boiling Point | 100 °C |
| Density | 1.6 g/cm³ |
| Appearance | translucent crystals or white powder |
| Color | White tranparent |
| Odor | Odorless |
| Form | Solid |
| Water Solubility | 680 g/L (20 ºC) |
| Refractive Index | 1.489 |
| pH | 6.0-7.5 (100g/l, H2O, 20℃) |
| Log P | -0.428 (est) |
Trade & Regulatory
| HS Code | 28323000 |
| Storage Class | 11 - Combustible Solids |
| WGK (Germany) | 1 |
Other Names
HypoANTICHLORsodium subsulfiteSODIUM THIOCYANATESODIUM THIOSULFATESODIUM HYPOSULFITE
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Raw Materials
Derivatives
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