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.

Arsenic trisulfide

Names
Preferred IUPAC name Arsenic trisulfide
Other names Arsenic(III) sulfide Orpiment Sulphuret of arsenic
Identifiers
CAS Number	1303-33-9 Y
3D model (JSmol)	Interactive image
ChemSpider	21241348 Y
ECHA InfoCard	100.013.744
EC Number	215-117-4
PubChem CID	4093503
RTECS number	CG2638000
UNII	44SIJ800OX Y
CompTox Dashboard (EPA)	DTXSID50274153
SMILES S1[As]3S[As]2S[As](S[As]1S2)S3
Properties
Chemical formula	As2S3
Molar mass	246.02 g·mol−1
Appearance	Orange crystals
Density	3.43 g cm−3
Melting point	310 °C (590 °F; 583 K)
Boiling point	707 °C (1,305 °F; 980 K)
Magnetic susceptibility (χ)	-70.0·10−6 cm3/mol
Structure[1]
Space group	P21/n (No. 11)
Lattice constant	a = 1147.5(5) pm , b = 957.7(4) pm , c = 425.6(2) pm α = 90°, β = 90.68(8)°, γ = 90°
Coordination geometry	pyramidal (As)
Hazards
NFPA 704	0 3 0
U.S. Permissible exposure limit (PEL)	[1910.1018] TWA 0.010 mg/m3
Related compounds
Other anions	{{{value}}}
Other cations	{{{value}}}
Related compounds	{{{value}}}
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

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.