Arsenite

The arsenite ion is AsO₃³⁻.An arsenite (compound) is any compound that contains this ion.The arsenic atom in arsenite has a valency of 3 and is also known as trivalent arsenic or As(III).

Arsenite resembles phosphite in many respects, since arsenic and phosphorus occur in the same group (column) of the periodic table.

The arsenite ion may be formed from arsenic trioxide by adding base.

Its white odorless crystals are toxic and very soluble in water. It occurs in nature as arsenolite and claudetite and is also a by-product of metal smelting. Its main use is in producing copper chrome arsenate to treat timber. It is also used for arsenic pesticides, glass production, pharmaceuticals and non-ferrous alloys.

Addendum

The definition above is incomplete. In fields that commonly deal with groundwater chemistry, arsenite commonly refers to As₂O₃ and sodium arsenite refers to NaAsO₂. Sodium arsenite is used in the water gas shift reaction to remove carbon dioxide.

Bacteria using and generating arsenate

Some species of bacteria obtain their energy by oxidizing various fuels while reducing arsenates to form arsenites. The enzymes involved are known as arsenate reductases.

In 2008, bacteria were discovered that employ a version of photosynthesis with arsenites as electron donors, producing arsenates (just like ordinary photosynthesis uses water as electron donor, producing molecular oxygen). The researchers conjectured that historically these photosynthesizing organisms produced the arsenates that allowed the arsenate-reducing bacteria to thrive. [ [http://www.rsc.org/chemistryworld/News/2008/August/15080802.asp Arsenic-loving bacteria rewrite photosynthesis rules] , Chemistry World, 15 August 2008]

References

External links

* [http://www.atsdr.cdc.gov/HEC/CSEM/arsenic Case Studies in Environmental Medicine - Arsenic Toxicity]
* [http://www.chemicalland21.com/industrialchem/inorganic/ARSENIC%20TRIOXIDE.htm Page at chemicalland21.com]