From Wikipedia, the free encyclopedia

Arsenic pentoxide
Other names	Arsenic(V) oxide Arsenic oxide Arsenic anhydride
Identifiers
CAS number	1303-28-2 Y
PubChem	14771
EC number	215-116-9
RTECS number	CG2275000
SMILES	O=[As](=O)O[As](=O)=O
InChI	1/As2O5/c3-1(4)7-2(5)6
InChI key	COHDHYZHOPQOFD-UHFFFAOYAN
ChemSpider ID	14088
Properties
Molecular formula	As2O5
Molar mass	229.8402 g/mol
Appearance	white hygroscopic powder
Density	4.32 g/cm3
Melting point	315 °C (decomposes)
Solubility in water	59.5 g/100 mL (0 °C) 65.8 g/100 mL (20 °C) 8.20 g/100 mL (100 °C)
Solubility	soluble in alcohol
Acidity (pKa)	7
Hazards
EU classification	Very toxic (T+) Carc. Cat. 1 Dangerous for the environment (N)
R-phrases	R45, R23/25, R50/53
S-phrases	S53, S45, S60, S61
NFPA 704	0 4 0
LD50	8 mg/kg (rat, oral)
Related compounds
Other cations	Phosphorus pentoxide Antimony pentoxide
Related compounds	Arsenic trioxide Arsenic acid
Y (what is this?)  (verify) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Arsenic pentoxide, As₂O₅, is an important commercial compound of arsenic. Its usage with respect to arsenic chemistry, as well as its toxicology are similar to arsenic trioxide, As₂O₃. Arsenic pentoxide is used as a solid or as a solution in the manufacturing of arsenates, weed killer, metal adhesives, insecticides, fungicides, wood preservatives, and colored gases and in printing and dyeing.^[1]

Synthesis

Arsenic pentoxide can be synthesized either by burning elemental arsenic in surplus of oxygen, or by oxidizing arsenic trioxide with oxidizing agents such as ozone, hydrogen peroxide and nitric acid.

Reactions

Arsenic pentoxide decomposes to oxygen and As₂O₃ upon heating^[2] forming arsenic trioxide. It is an oxidizing agent, liable to react vigorously with oxidizable substances — for example, it liberates chlorine from hydrochloric acid.

As₂O₅ dissolves readily in water to form arsenic acid, H₃AsO₄.^[3]

Bibliography

Arsenic: Medical and Biological Effects of Environmental Pollutants (1977)

References

1. ^ Arsenic Pentoxide, Systemic Agent. National Institute for Occupational Safety and Health. Emergency Response Safety and Health Database. August 22, 2008. Retrieved December 22, 2008.
2. ^ Martin Jansen (1977). "Crystal Structure of As₂O₅". Angewandte Chemie International Edition in English 16 (5): 314–315. doi:10.1002/anie.197703142.  
3. ^ Greenwood, Norman N.; Earnshaw, A. (1997), Chemistry of the Elements (2nd ed.), Oxford: Butterworth-Heinemann, ISBN 0-7506-3365-4   pp. 576-577

External links

• Arsenic Pentoxide. National Institute for Occupational Safety and Health.
• International Chemical Safety Card 0377
• NIOSH Pocket Guide to Chemical Hazards
• IARC Monograph – Arsenic and Arsenic Compounds
• NTP Report on Carcinogens – Inorganic Arsenic Compounds
• European Chemicals Bureau
• Institut national de recherche et de sécurité (1992). "Arsenic et composés minéraux."PDF Fiche toxicologique n° 192. Paris:INRS. (French)
• Linstrom, P.J.; Mallard, W.G. (eds.) NIST Chemistry WebBook, NIST Standard Reference Database Number 69. National Institute of Standards and Technology, Gaithersburg MD. http://webbook.nist.gov