Sodium Thiosulfate Supplier :
Brief Introduction
Appearance: Colorless crystalline
Molecular formula: Na2S2O3·5H2O
Molecular Mass: 248.18
CAS No: 10102-17-7
Specification
Assay: 98% min
Insolubility: 0.03% max
pH: 6.5-9.5
Characteristic
Sodium Thiosulfate’sdensity is 1.79g/cm3, and its melting point is 40-45℃.
It is soluble in water, turpentine and ammonia, insoluble in alcohol. No foul, tasted salty. Heated to 100 ℃, it will lose all of crystal water, and go on burning will broken down into sodium sulfate and sodium sulfide.
At 33 ℃ or more, Sodium Thiosulfate was easily weathered in dry air and absorptive in humidity.
Applications
Water treatment:
Sodium thiosulfate can be used to lower chlorine levels in swimming pools and spas following super chlorination.
Sodium thiosulfate can be used in bleach.
Sodium thiosulfate can be used in pH testing of bleach substances. The universal indicator and any other liquid pH indicator are destroyed by bleach, rendering them useless for testing the pH. If one first adds sodium thiosulfate to such solutions, it will neutralize the color-removing effects of bleach and allow one to test the pH of bleach solutions with liquid indicators. The relevant reaction is akin to the iodine reaction: thiosulfate reduces the hypochlorite (active ingredient in bleach) and in so doing becomes oxidized to sulfate.
In analytical chemistry, the most important use comes from the fact that the thiosulfate anion reacts stoichiometrically with iodine, reducing it to iodide as it is oxidized to tetrathionate. It can, when heated with a sample containing aluminum cation, produce a white precipitation.
In photographic processing, the terminal sulfur atom in S2O32− binds to soft metals with high affinity. Thus, silver halides, e.g. AgBr, typical components of photographic emulsions, dissolve upon treatment with aqueous thiosulfate:
In gold extraction, sodium thiosulfate is one component of an alternative lixiviant to cyanide for extraction of gold.[3] It forms a strong complex with gold(I) ions, [Au(S2O3)2]3-. The advantage of this approach is that thiosulfate is essentially non-toxic and that ore types that are refractory to gold cyanidation (e.g. carbonaceous or Carlin type ores) can be leached by thiosulfate. Some problems with this alternative process include the high consumption of thiosulfate, and the lack of a suitable recovery technique, since [Au(S2O3)2]3- does not adsorb to activated carbon, which is the standard technique used in gold cyanidation to separate the gold complex from the ore slurry.
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