Magnesium thiosulfate hexahydrate Property

Melting point:

1700°C

Density 

1.818

Water Solubility 

g/100g solution H2O: 30.69 (0°C), 34.51 (28°C); solid phase, MgS2O3 · 6H2O [KRU93]; insoluble alcohol [MER06]

Merck 

14,5694

CAS DataBase Reference

10124-53-5(CAS DataBase Reference)

EPA Substance Registry System

Thiosulfuric acid (H2S2O3), magnesium salt (1:1) (10124-53-5)

Safety

Hazard Codes 

Xi

Risk Statements 

36/37/38

Safety Statements 

26-36

WGK Germany 

3

RTECS 

XN6550000

Toxicity

mouse,LD50,subcutaneous,850mg/kg (850mg/kg),Arzneimittel-Forschung. Drug Research. Vol. 5, Pg. 376, 1955.

Hazard and Precautionary Statements (GHS)

Symbol(GHS)

Signal word

Warning

Hazard statements

H315Causes skin irritation

H319Causes serious eye irritation

H335May cause respiratory irritation

Precautionary statements

P264Wash hands thoroughly after handling.

P264Wash skin thouroughly after handling.

P280Wear protective gloves/protective clothing/eye protection/face protection.

P302+P352IF ON SKIN: wash with plenty of soap and water.

P305+P351+P338IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continuerinsing.

P321Specific treatment (see … on this label).

P332+P313IF SKIN irritation occurs: Get medical advice/attention.

P362Take off contaminated clothing and wash before reuse.

Magnesium thiosulfate hexahydrate Chemical Properties,Usage,Production

Description

Magnesium thiosulfate has the molecular formula of MgS₂O₃ and the molecular weight of 136.4352 g/mol. It is also known as “hyposulfite”. It can be prepared by the reaction of sodium thiosulfate upon the chloride in water:
MgCl2+Na2S2O3? MgS2O3+2NaCl
Since magnesium thiosulfate is soluble in water (50 g/100 ml at 20°C), the solution must be evaporated at a low temperature to crystallize the product (salt-out temperature ～15°F (-9.4°C). A hexahydrate, MgS₂O₃· 6H₂O, is the result.
These are colorless crystals that lose water at 170°C to form the trihydrate. Further heating to 420°C then forms the anhydrate. Further heating to 600°C will cause the production of magnesium sulfate, sulfur and oxides of sulfur:
2MgS2O3+2O2+heat? 2MgSO4+S+SO2 Magnesium thiosulfate is considered to have a low toxicity to humans. It has been used to remove ozone from either a water stream, such as a drinking water or wastewater stream being treated with ozone, or scrubbing ozone from a gaseous stream by contacting the gaseous stream with solid magnesium thiosulfate. It has also been used to remove chlorine gas from a water stream by contacting the stream with magnesium thiosulfate solution. In yet another aspect, a method of scrubbing chlorine from a gaseous stream comprises contacting the gas stream with solid magnesium thiosulfate.
Magnesium thiosulfate is not commonly referenced in scientific literature. The few articles that prevail discuss technically specific physical properties of the end product itself. Synthetic methods are described in some Japanese patents and there is mention of MgTS in a short German description in Handbuch der Anorganischen Chemie, vol. 11, 1984. Both refer to adding sulfur to magnesium sulfite to produce magnesium thiosulfate. Neither reference describes the pH nor physical consistency of the “sulfite” intermediate, although the German article does note the “color change” observed as SO₂ is purged into MgO: the slurry becomes yellow.

Chemical Properties

colorless or white crystal(s) [MER06]