HOCl + 2 S2O32- Cl- + S4O62- + OH-
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Dissolved oxygen testing and chemical analysis of oxidants. Thiosulfate is a reducing titrant used for determining many oxidizing agents. For example, hypo chlorite concentrations in bleach can be determined using the reaction above. Thiosulfate is also used as a titrant in determining (the extent to which oxygen within a sample can support microbial life) [].
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Whitening cotton fabrics, bone, straw, and ivory. Some materials are weakened or yellowed when bleached. Thiosulfate solutions can sometimes be used to whiten these materials. See []
Where does thiosulfate ion come from?
Thiosulfate is produced industrially by several different reactions:
- Reaction of sulfur with sodium sulfite in boiling aqueous solution,
S8 + 8 SO32- 8 S2O32-
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Reaction of SO2 gas with sulfide/carbonate liquor (a byproduct of paper manufacturing).
- As a byproduct in the manufacture of sulfur dyes.
What is thiosulfate ion?
Thiosulfate (S2O32-) is an oxyanion of sulfur produced by the reaction of sulfite ions with elemental sulfur in boiling water,
S(s) + SO32-(aq) S2O3-2(aq)
Thiosulfate occurs naturally in , and is produced by certain biochemical processes. In the body, thiosulfate converts small amounts of ion into harmless products and plays a role in the biosynthesis of cysteine, a sulfur-containing that locks proteins into their correct three-dimensional shapes. Thiosulfate is not found in large quantities in nature. Solutions of thiosulfate break down into sulfur, sulfites, and sulfates when exposed to acids, light, metal ions, and bacteria.
Thiosulfate is a reducing agent. It is routinely used as a titrant to determine concentrations of oxidants such as hypochlorite in bleach and dissolved oxygen in water. It instantly dechlorinates water, and is used to stop bleaching action in the papermaking industry. Thiosulfate forms water-soluble complexes with many metals, making it useful in photo processing (where it dissolves excess silver bromide on the surface of exposed film, preventing excessive darkening). Thiosulfate is also useful in the extraction of silver from silver ore, in leather manufacture, and as a mordant in the textile industry.
