| IUPAC name
| Other names
Thiosulfuric acid, ammonium salt (1:2)
Thiosulfuric acid, diammonium salt
|Molar mass||148.20 g/mol|
|Appearance||Colorless crystalline solid|
|Density||1.679 g/cm3 (at 25 °C)|
|Melting point||150 °C (302 °F; 423 K) (decomposition)|
| Very soluble in cold water|
1.033 g/ 100 ml (at 100 °C)
|Solubility|| Slightly soluble in acetone|
Insoluble in benzene, diethyl ether, ethanol, toluene
|Safety data sheet||Sigma-Aldrich|
|Lethal dose or concentration (LD, LC):|
LD50 (Median dose)
|2,890 mg/kg (rat, oral)|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Ammonium thiosulfate is an inorganic compound with the formula (NH4)2S2O3.
Ammonium thiosulfate is a colorless crystalline solid, soluble in water but less soluble in organic solvents. It has a slight ammonia odor. Its decomposition is noticeable above 50 °C.
Ammnoium thiosulfate is sold as fertilizer, as aqueous solution. THIO-S is one such product. It contains 30-60% ammonium thiosulfate by mass. To obtain the pure compound, gently heat the solution for several hours at ~90 °C, then cool the concentrated solution to crystallize the compound.
Ammonium thiosulfate is also available as photographic fixer.
Ammonium thiosulfate can be produced by mixing two solutions of ammonium sulfate and sodium thiosulfate, followed by cooling, filtration of the sodium sulfate. The filtrate is concentrated and cooled to recrystallize the compound.
- Reducing agent
- Prevent the formation of dioxins and furans in coal wastes
Ammonium thiosulfate releases ammonia gas over time which is irritant.
In closed bottles, in well ventilated places. Storage temperature should be below 50 °C.
No special disposal is required, though it's best to strongly dilute it before pouring it down the drain or soil.