Arsenic (V) oxide

Crystal structure
	__ As 5+ __ O 2−
General
Surname	Arsenic (V) oxide
other names	Diarsenic pentoxide; Arsenic anhydride; Arsenic anhydride;
Ratio formula	As 2 O 5
Brief description	white, odorless solid
External identifiers / databases
EC number	215-116-9
ECHA InfoCard	100.013.743
PubChem	14771
Wikidata	Q411256
properties
Molar mass	229.84 g mol −1
Physical state	firmly
density	4.32 g cm −3
Melting point	315 ° C (decomposes into arsenic trioxide and oxygen)
solubility	easily soluble in water
safety instructions
H and P phrases	H: 300-331-350-410
	P: 201-261-264-273-301 + 310-311
Authorization procedure under REACH	of particular concern : carcinogenic ( CMR ); subject to approval
MAK	DFG : canceled as carcinogenic; Switzerland: 0.1 mg m −3 (based on arsenic, measured as inhalable dust );
Toxicological data	8 mg kg −1 ( LD 50 , rat , oral )
Thermodynamic properties
ΔH f 0	−924.9 kJ / mol
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Arsenic (V) oxide or diarsene pentoxide is the pentavalent oxide of arsenic and an arsenic compound that is often used industrially. It is used in a similar way to arsenic trioxide (e.g. as a fungicide and pesticide ).

Extraction and presentation

Diarsenic pentoxide is produced by oxidizing arsenic trioxide with oxidizing agents such as ozone , hydrogen peroxide or nitric acid .

properties

Arsenic (V) oxide is a white, amorphous to glassy, odorless and hygroscopic compound. When heated above 315 ° C it decomposes into arsenic trioxide and oxygen .

It is easily soluble in water and quickly forms arsenic acid

${\ displaystyle \ mathrm {As_ {2} O_ {5} +3 \ H_ {2} O \ rightleftharpoons 2 \ H_ {3} AsO_ {4}}}$

Arsenic (V) oxide crystallizes orthorhombically , space group P 2 ₁ 2 ₁ 2 ₁ (space group no. 19) , with the lattice parameters a = 8.646 Å , b = 8.45 Å and c = 4.626 Å. A tetragonal high-temperature shape with the space group P 4 ₁ 2 ₁ 2 (No. 92) and the lattice parameters a = 8.572 Å and c = 4.636 Å is also known. Template: room group / 19 Template: room group / 92

Safety instructions and legal restrictions

Diarsenic pentoxide attacks many metals in connection with moisture , as arsenic (V) acid is formed on contact with water . The substance is very toxic and was added to the candidate list of substances of very high concern (SVHC) in August 2008 due to its classification as carcinogenic (Carc. 1A) . In February 2012, diarsenic pentoxide was also included in the list of substances subject to authorization with the expiry date for use in the EU on May 21, 2015. As an arsenic compound, arsenic pentoxide is also subject to the restrictions in Annex XVII, number 19 of the REACH regulation .

Individual evidence

↑ ^a ^b ^c ^d ^e ^f ^g Entry on arsenic (V) oxide in the GESTIS substance database of the IFA , accessed on February 1, 2016(JavaScript required) .
↑ Entry on Diarsenic pentaoxide in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .
↑ ^a ^b Entry in the SVHC list of the European Chemicals Agency , accessed on July 15, 2014.
↑ Entry in the register of substances subject to authorization of the European Chemicals Agency , accessed on July 15, 2014.
↑ Swiss Accident Insurance Fund (Suva): Limits - Current MAK and BAT values (search for 1303-28-2 or arsenic (V) oxide ), accessed on October 24, 2016.
↑ chemicalland21.com: ARSENIC PENTOXIDE , accessed June 11, 2013.
↑ David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Standard Thermodynamic Properties of Chemical Substances, pp. 5-5.
↑ scorecard.org: ARSENIC PENTOXIDE , accessed June 11, 2013.
↑ M. Jansen: Crystal structure of As ₂ O ₅ . In: Angewandte Chemie , 89, 1977, pp. 326-327, doi : 10.1002 / anie.19770890511 .
↑ Martin Jansen: On a new modification of As ₂ O ₅ . In: Journal of Nature Research B . 34, 1979, pp. 10-13 ( PDF , free full text).
↑ Regulation (EU) No. 125/2012
↑ ECHA: List of restricted substances - Annex XVII of the REACH regulation , accessed on August 12, 2020.

[GESTIS-1] ↑ ^a ^b ^c ^d ^e ^f ^g Entry on arsenic (V) oxide in the GESTIS substance database of the IFA , accessed on February 1, 2016(JavaScript required) .

[CLP_100.013.743-2] Entry on Diarsenic pentaoxide in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .

[SVHC-3] Entry in the SVHC list of the European Chemicals Agency , accessed on July 15, 2014.

[Zulassungspflicht-4] Entry in the register of substances subject to authorization of the European Chemicals Agency , accessed on July 15, 2014.

[5] Swiss Accident Insurance Fund (Suva): Limits - Current MAK and BAT values (search for 1303-28-2 or arsenic (V) oxide ), accessed on October 24, 2016.

[6] 21.com: ARSENIC PENTOXIDE , accessed June 11, 2013.

[CRC90_5_5-7] David R. Lide (Ed.): CRC Handbook of Chemistry and Physics . 90th edition. (Internet version: 2010), CRC Press / Taylor and Francis, Boca Raton, FL, Standard Thermodynamic Properties of Chemical Substances, pp. 5-5.

[8] scorecard.org: ARSENIC PENTOXIDE , accessed June 11, 2013.

[9] M. Jansen: Crystal structure of As ₂ O ₅ . In: Angewandte Chemie , 89, 1977, pp. 326-327, doi : 10.1002 / anie.19770890511 .

[10] Martin Jansen: On a new modification of As ₂ O ₅ . In: Journal of Nature Research B . 34, 1979, pp. 10-13 ( PDF , free full text).

[Verordnung_(EU)_Nr._125/2012-11] Regulation (EU) No. 125/2012

[beschränkte_stoffe-12] ECHA: List of restricted substances - Annex XVII of the REACH regulation , accessed on August 12, 2020.