Arsenic pentasulfide
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| Names | |
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| IUPAC name
Arsenic pentasulfide
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Other names
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| Identifiers | |
3D model (JSmol)
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| ChemSpider | |
| ECHA InfoCard | 100.154.195 |
| EC Number |
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PubChem CID
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| UNII | |
| UN number | 1557 |
CompTox Dashboard (EPA)
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| Properties | |
| As2S5 | |
| Molar mass | 310.14 g·mol−1 |
| Appearance | Vivid, yellow, opaque crystals[1] |
| Melting point | 300 °C (572 °F; 573 K)(minimum) |
| Boiling point | 500 °C (932 °F; 773 K)(decomposes) |
| 0.014 g/L (0 °C (32 °F; 273 K)) | |
| Hazards | |
| GHS labelling: | |
 
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| Danger | |
| H301, H331, H410 | |
| P261, P264, P270, P271, P273, P301+P310, P304+P340, P311, P321, P330, P391, P403+P233, P405, P501 | |
| Related compounds | |
Other anions
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Other cations
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references
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Arsenic pentasulfide is an inorganic compound containing arsenic and sulfur. It has the approximate formula As2S5, and is a somewhat brighter yellow color than arsenic trisulfide.[1]
Uses
As2S5 has been used as a pigment and chemical intermediate but is generally only of interest in academic laboratories.[2]
Preparation
Arsenic pentasulfide is prepared by precipitation from an acidic solution of soluble As(V) salts by treatment with hydrogen sulfide (H2S).[3]
A similar preparation is by treatment of an ice-cooled aqueous solution of orthoarsenic acid (H3AsO4) with twice its volume of concentrated hydrochloric acid, rapid bubbling of H2S into the solution for an hour, followed by washing of the precipitate with water and alcohol:[1]
- 2 H3AsO4 + 5 H2S → As2S5 + 8 H2O
It may be also prepared by heating a mixture of arsenic and sulfur, extracting the fused mass with an ammonia solution and reprecipitating arsenic pentasulfide at low temperature by addition of hydrochloric acid.
Reactions
Arsenic pentasulfide decomposes to arsenic trioxide (As2O3), sulfur, and arsenic trisulfide (As2S3) when boiled in water.[1]
It oxidizes in air at elevated temperatures producing arsenic oxides, the products and yields of which are variable. In alkali metal sulfide solutions arsenic pentasulfide forms a thioarsenate anion, [AsS4]3−, which contain As(V) centers.
References
- ^ a b c d Schenk, P.W. (2012) [1963]. "10. Arsenic, Antimony, Bismuth". In Brauer, Georg (ed.). Handbook of Preparative Inorganic Chemistry. Vol. 1 (2nd ed.). New York, NY: Academic Press. p. 603. ISBN 9780323161275.
- ^ Emelina, A. L.; Alikhanian, A. S.; Steblevskii, A. V.; Kolosov, E. N. (February 2007). "Phase diagram of the As-S system". Inorganic Materials. 43 (2): 95–104. doi:10.1134/S002016850702001X.
- ^ Norman, N.C., ed. (1998). Chemistry of arsenic, antimony and bismuth. London: Blackie Acad. & Professional. pp. 114–5. ISBN 978-0-7514-0389-3.