Arsenic sulfides

from Wikipedia, the free encyclopedia

Arsenic sulfides are sulfide compounds of the chemical elements arsenic and sulfur in the form As x S y .

Forms of training

Various arsenic sulfides are known, three of which occur naturally:

  • Tetraarsensulfide As 4 S, as a mineral duranosite
  • Tetraarsentrisulfid As 4 S 3 , found in nature as the mineral dimorphine .
  • Arsenic (II) sulfide, tetraarsene tetrasulfide , As 4 S 4 , also arsenic disulfide As 2 S 2 , also indicated as AsS in the ratio formula
    Is known in nature as mineral realgar (α-As 4 S 4 ) and pararealgar (γ-As 4 S 4 ). It forms crystals, from red color (in the α structure, noise red ) to orange-yellow (γ structure)
  • Arsenic (III) sulfide , tetra- arsenic hexasulfide As 4 S 6 or arsenic trisulfide As 2 S 3
    It forms orange to bright yellow crystals ( rusty yellow ). Arises in nature as a mineral auripigment . As a pigment auripigment exclusively in a pure golden yellow form ( royal yellow ).
  • Arsenic (V) sulfide , arsenic pentasulfide As 2 S 5 does not occur in nature. It's a lemon yellow powder.
  • As 4 S 5 , as the mineral uzonite

structure

Arsenic sulfides generally have the empirical formula As 2 S n , but usually form complex cage structures of the form As 4 S n . Arsenic is three- bonded , i.e. it forms a bond with three other atoms (sulfur or arsenic). Sulfur is double-bonded and forms a bridge between two arsenic atoms.

Arsenic pentasulphide is the exception, since in this compound there is an additional double bond to sulfur on each arsenic atom .

In the solid state, arsenic (III) sulfide is present as As 2 S 3 in a polymeric structure, the cage structure (here: adamantane structure) only forms in the gas phase.

  • Ace 4 S 4 (Realgar)

  • As 2 S 3 (Orpiment) in the solid state

  • Adamantane structure

properties

Arsenic sulfides are generally sparingly soluble in water and are therefore not toxic in their pure state .

  • In the air, however, a small amount of arsenic (III) oxide ( arsenic ) is usually formed .
  • As 2 S 3 (Orpiment) is not soluble in water and acids, so it is not broken down by hydrochloric acid in the stomach . As 4 S 4 (Realgar) is soluble in alkaline solutions and forms toxic vapors with acids and both with potassium hydroxide .
  • the arsenic sulphides react to arsenic (III) oxide and sulfur or sulfur dioxide when burned
  • Both pure arsenic and arsenic (III) oxide as arsenolite appear in yellow modifications. These can be found in natural occurrences as well as synthetic products

Arsenic trioxide is one of the most toxic minerals and it is carcinogenic and harmful to many living things. The orally ingested, lethal dose for humans can be less than 0.1 g. For these reasons, all arsenic sulfides are generally considered to be highly toxic and environmentally harmful and are subject to the strictest safety regulations.

Arsenic sulfides
Surname Arsenic (II) sulfide Arsenic (III) sulfide Arsenic (V) sulfide
other names
Natural occurrence Realgar Auripigment
Molecular formula As 4 S 4 As 2 S 3 As 2 S 5
CAS number 1303-32-8 1303-33-9 1303-34-0
PubChem 139298 71586773 3371533
Molar mass 427.92 g mol −1 246.04 g mol −1 310.14 g mol −1
Physical state firmly firmly
Brief description Pieces or crystalline powder
golden yellow, odorless
Melting point 300… 325 ° C > 300 ° C
density 3.46 g cm −3
Solubility in water 0.51 mg l −1 at 18 ° C
GHS
labeling 		from  Regulation (EC) No. 1272/2008 (CLP) , expanded if necessary
06 - Toxic or very toxic 09 - Dangerous for the environment
danger 		from  Regulation (EC) No. 1272/2008 (CLP) , expanded if necessary
06 - Toxic or very toxic 09 - Dangerous for the environment
danger 		from  Regulation (EC) No. 1272/2008 (CLP) , expanded if necessary
06 - Toxic or very toxic 09 - Dangerous for the environment
danger
H and P phrases 301-331-410 301-331-410 301-331-410
? 270-273-302 + 352-309 + 310-501 261-273-301 + 310 + 330-304 + 340 + 312-391-403 + 233

Artificial manufacture

Most arsenic sulfides can be obtained by melting arsenic and sulfur together in the appropriate proportions. Arsenic (V) sulfide is formed from arsenic acid and hydrogen sulfide.

literature

Web links

Individual evidence

  1. ↑ a b c d e f Entry for CAS no. 1303-33-9 in the GESTIS substance database of the IFA , accessed on January 27, 2017 (JavaScript required)
  2. ↑ a b c Datasheet Arsenic (V) sulfide from Sigma-Aldrich , accessed on January 27, 2017 ( PDF ).
  3. ↑ Entry on arsenic (II) sulfide in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on January 27, 2017. Manufacturers or distributors can expand the harmonized classification and labeling .
  4. ↑ Not explicitly listed in Regulation (EC) No. 1272/2008 (CLP) , but with the specified labeling it falls under the group entry arsenic compounds, with the exception of those named in this appendix in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA) on January 27, 2017. Manufacturers or distributors can expand the harmonized classification and labeling .
  5. ↑ Entry on arsenic (V) sulphide in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on January 27, 2017. Manufacturers or distributors can expand the harmonized classification and labeling .
  6. ↑ G. Brauer (Ed.), Handbook of Preparative Inorganic Chemistry 2nd ed., Vol. 1, Academic Press 1963, p. 603.