Arsenic trisulfide

Arsenic trisulfide, also known as orpiment or arsenic(III) sulfide, is a chemical compound. Its chemical formula is As2S3. It has arsenic and sulfide ions in it. The arsenic is in its +3 oxidation state.

Properties
Arsenic trisulfide is a yellow solid. It is a semiconductor. It has a glass (amorphous) form and a crystalline form. It burns in air to make sulfur dioxide and arsenic trioxide, which makes a highly toxic smoke. Arsenic trisulfide can oxidize on the surface to make a highly toxic layer of arsenic trioxide as well. Arsenic trisulfide is not toxic unless it oxidizes. It does not react with acids.

Occurrence
Arsenic trisulfide is found as the mineral orpiment.

Preparation
Arsenic trisulfide is made when an arsenic compound like arsenic trichloride reacts with hydrogen sulfide. It is also made when arsenic and sulfur are heated together. 

Uses
It was looked at for treating cancer. It was used by the Egyptians as a pigment and cosmetic. It is used in glass. 

References

Related pages
Arsenic tribromide
Antimony sulfide
Bismuth trisulfide

Category:Arsenic compounds
Category:Sulfur compounds