Sodium Thiosulfate Pentahydrate, ACS Grade

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Sodium Thiosulfate Pentahydrate, also known as Disodium Sulfurothioate Pentahydrate, and Sodium Hyposulfite Pentahydrate is a hydrate of Sodium Thiosulfate with 5 mol eq. of Water. having the chemical formula H10Na2O8S2 or Na2S2O3-5H2O. It appears as colorless to whitehygroscopic crystals, chunks, or crystalline powder with no odor. It is sparingly soluble in Water and insoluble in Alcohol at ambient conditions. When heated to around 300 o C, it undergoes decomposition emitting highly toxic fumes of Disodium Oxide and Sulfur Oxides. Commercially, it is produced by reacting by-product liquid of Sodium Sulfide synthesis with Sulfur Dioxide. An ACS Grade reagent is a chemical that meets the purity requirements of the American Chemical Society. For dependable, consistent, and repeatable findings, ACS Grade reagents can be utilized in high-quality research labs. In the United States of America (USA), Lab Alley sells its high- quality Ammonium Molybdate Crystal, Tetrahydrate, ACS Grade online at


Sodium Thiosulfate Crystal Pentahydrate Features:

Assay 99.5-101.0%
pH of a 5% solution @ 25°C 6.0-8.4
Insoluble Matter 0.005%
Nitrogen Compounds (as N) 0.002%
Sulfate and Sulfite (as SO4) 0.1%
Sulfide (as S) To Pass Test (limit about 1 ppm)
Common Uses
  • Reagent
  • Chemical precursor
  • Volumetric analysis
Commercial/industrial applications
  • Photographic processing
  • Hand warmers/heating pads
  • Refining of gold
Safety and Handling

Please contact us to request a Safety Data Sheet (SDS) and Certificate of Analysis (COA) for Sodium Thiosulfate Crystal Pentahydrate ACS.