Arsenic pentoxide

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A 3D-model of arsenic pentoxide.

Arsenic pentoxide, also known as arsenic(V) oxide, is a chemical compound. Its chemical formula is As2O5. It has arsenic and oxide ions in it. The arsenic is in its +5 oxidation state. More common is arsen in its oxidation state +3 as As2O3 (arsenic trioxide or arsenic(III) oxide). The LD50 for arsenic pentoxide is 8mg/kg for rats.[1] When the substance becomes wet, it turns into arsenic acid, which corrodes metals.

Properties[change | change source]

Arsenic pentoxide is a white, odourless solid.[1] It dissolves easily in water to make arsenic acid. It is highly toxic, as are almost all arsenic compounds.[1][2][3] It is a powerful oxidizing agent. It reacts with hydrochloric acid to make chlorine. As2O5 breaks down to arsenic trioxide and oxygen when heated to about 300°C.[4]

As_2O_5 + 268.1 kJ \rightarrow As_2O_3 + O_2

It reacts with bases to make arsenates. The energy for the reaction is taken from the heating.

Preparation[change | change source]

Arsenic pentoxide cannot be produced by burning arsen. That only results in As2O3. To produce arsenic pentoxid, arsenic acid will be dehydrated. This is done with phosphorus(V) oxide.

2 H_3AsO_4 \rightleftharpoons As_2O_5 + 3 H_2O

The arsenic pentoxide drops out as white powder.[5]

Uses[change | change source]

Arsenic pentoxide is used to make pesticides and insecticides. It is also used in glass industry.[6]

Related pages[change | change source]

References[change | change source]

  1. 1.0 1.1 1.2 "ARSENIC PENTOXIDE". chemicalland21.com. 2012 [last update]. http://www.chemicalland21.com/industrialchem/inorganic/ARSENIC%20PENTOXIDE.htm. Retrieved 6 August 2012.
  2. "Toxicity of Arsenic Compounds". ncbi.nlm.nih.gov. 2012 [last update]. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1039212/?page=1. Retrieved 6 August 2012.
  3. "ARSENIC Toxicity". manbir-online.com. 2012 [last update]. http://manbir-online.com/diseases/arsenic.htm. Retrieved 6 August 2012.
  4. Wiberg, Nils; Arnold Holleman (2007). Lehrbuch der Anorganischen Chemie. Berlin, New York: de Gruyter. p. 845. ISBN 978-3-11-017770-1 .
  5. Wiberg, Nils; Arnold Holleman (2007). Lehrbuch der Anorganischen Chemie. Berlin, New York: de Gruyter. p. 844. ISBN 978-3-11-017770-1 .
  6. "Arsenic pentoxide Manufacturers Suppliers in China CAS No 1303-28-2 | Xilan Chemicals Co Ltd Leading Chemical Manufacturer and Trader". xilanchem.com. 2012 [last update]. http://xilanchem.com/arsenic-pentoxide-manufacturers-suppliers-in-china-cas-no-1303-28-2. Retrieved 6 August 2012.