Physical and chemical properties:
Ammonium thiosulfate is a colorless, transparent liquid or white crystal. The relative density of crystals is 1.679. It is very soluble in water and has a solubility of 103.3g/100ml water at 100 °C. Ammonium thiosulfate is insoluble in alcohol and ether, but slightly soluble in acetone. When the ammonium thiosulfate is heated to 150 ° C, it decomposes to form ammonium sulfite, sulfur, ammonia, hydrogen sulfide and water. Ammonium thiosulfate is very unstable in air and stable in ammonia.
Method for preparing ammonium thiosulfate:
An excess of ammonium carbonate can be added to an aqueous solution of calcium thiosulfate to prepare ammonium thiosulfate. It is also possible to prepare ammonium thiosulfate by reacting ammonium hydrogen sulphate with ammonium hydrogen sulfite in an accurate molar ratio of 1:2. It is also possible to carry out a metathesis reaction with ammonium sulfite and ammonium polysulfide, and then remove the willow to obtain ammonium thiosulfate by freeze crystallization. Ammonium thiosulfate is unstable and can only be obtained at low temperature crystallization.
Use of ammonium thiosulfate:
Ammonium thiosulfate can be used as a photographic fixer in the photographic industry. Ammonium thiosulfate is more soluble in the silver halide emulsion than the sodium salt. It has the advantage of short washing time and easy silver recovery. Ammonium thiosulfate is also used as a main component of a silver plating bath, a detergent on a metal surface, and an aluminum-magnesium gold casting protectant. It is used as a bactericide and analytical reagent in medicine.