Sodium Thiosulphate Pentahydrate 99% (CAS Number: 10102-17-7, EC Number: 231-867-5) is easily soluble in water, allowing for convenient usage and effective performance. The molecular formula of this compound is Na2S2O3·5H2O, and it has a density of 1.67 g/cm³.

Sodium Thiosulphate Pentahydrate 99% has a multitude of applications. In photography, it serves as a reliable fixing agent, removing excess silver halides to ensure image permanence. In water treatment processes, it effectively neutralizes chlorine, making it an ideal choice for dechlorinating. This compound is also widely used in chemical synthesis, including iodometric titrations, redox reactions, and as a reducing agent. Moreover, it finds application in educational experiments and demonstrations. In industrial settings, it acts as a dechlorinating agent, bleach activator, and source of sulphur, making it valuable in the mining, textile, and paper industries.

Sodium Thiosulphate Pentahydrate 99% is known for its exceptional solubility in water, which enables easy integration into various processes. Whether you require it for photography, water treatment, chemical synthesis, educational purposes, or industrial applications, this compound delivers reliable results and consistent performance.

As a component in hand warmers and other chemical heating pads that produce heat by exothermic crystallization of a supercooled solution.
In bleach
In pH testing of bleach substances.
To dechlorinate tap water for aquariums or treat effluent from waste water treatments prior to release into rivers. The reduction reaction is analogous to the iodine reduction reaction. Treatment of tap water requires between 0.1 grams and 0.3 grams of pentahydrated (crystalline) sodium thiosulfate per 10 litres of water.
To lower chlorine levels in swimming pools and spas following super chlorination.
To remove iodine stains, e.g. after the explosion of nitrogen triiodide.
In bacteriological water assessment.
In the tanning of leather.
To demonstrate the concept of reaction rate in chemistry classes.
To demonstrate the concept of supercooling in physics classes. Melted sodium thiosulfate is very easy to overcool to room temperature and when crystallization is forced, the sudden temperature jump to 48.3 deg C can be experienced by touch.
As part of patina recipes for copper alloys.
Often used in pharmaceutical preparations as an anionic surfactant to aid in dispersion.
It can also be used as a very interesting solute in supersaturation experiments.
As an ingredient to table salt
Gold Extraction
Antidote to cyanide poisoning
Photographic processing

Minimum Assay: >99.0%
Molecular Formula: Na2S2O3•5H2O
Molecular Weight: 241.17 g/mol
Solubility in water (% weight): 79g/100 ml water @ 40 C
Melting Point: 48 °C
Calcium (Ca): <0.30%
Iron (Fe): <10ppm
Heavy Metals (as Pb): <10ppm
Acidity: <0.01%
Alkalinity: <0.06%

Hazard Phrases: Not considered harmful under normal laboratory conditions

Cas No: 10102-17-7
Einecs No: 231-867-5