Chemistry: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 | |
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PubChem CID
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| UNII | |
| UN number | 1557 |
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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 pictograms |  
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| GHS Signal word | Danger |
| H301, H331, H410 | |
| P261, P264, P270, P271, P273, P301+310, P304+340, P311, P321, P330, P391, P403+233, 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). | |
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| Infobox references | |
Arsenic pentasulfide is an inorganic compound containing arsenic and sulfur. It has the approximate formula As
2S
5, and is a somewhat brighter yellow color than arsenic trisulfide.[1]
Uses
As
2S
5 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 (H
2S).[3]
A similar preparation is by treatment of an ice-cooled aqueous solution of orthoarsenic acid (H
3AsO
4) with twice its volume of concentrated hydrochloric acid, rapid bubbling of H
2S into the solution for an hour, followed by washing of the precipitate with water and alcohol:[1]
- 2 H
3AsO
4 + 5 H
2S → As
2S
5 + 8 H
2O
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.[citation needed]
Reactions
Arsenic pentasulfide decomposes to arsenic trioxide (As
2O
3), sulfur, and arsenic trisulfide (As
2S
3) 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, [AsS
4]3−, which contain As(V) centers.
References
- ↑ 1.0 1.1 1.2 1.3 Schenk, P.W. (2012). "10. Arsenic, Antimony, Bismuth". in Brauer, Georg. Handbook of Preparative Inorganic Chemistry. 1 (2nd ed.). New York, NY: Academic Press. p. 603. ISBN 9780323161275. https://archive.org/details/Handbook_of_Preparative_Inorganic_Chemistry_1_2_Brauer/page/n627/mode/1up.
- ↑ 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). [[[:Template:GBUrl]] Chemistry of arsenic, antimony and bismuth]. London: Blackie Acad. & Professional. pp. 114-5. ISBN 978-0-7514-0389-3. Template:GBUrl.
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