The selenate ion is .
Selenates are analogous to
sulfates and have similar chemistry. They are highly soluble in
aqueous solutions at ambient temperatures.
Unlike sulfate, selenate is a somewhat good
oxidizer; it can be reduced to
selenite or
selenium.
In strongly acidic conditions, the hydrogen selenate ion, , is formed. It corresponds to the
selenic acid, H
2SeO
4, which is a strong acid and can in its concentrated form dissolve
gold.
The element selenium exhibits several valence states. Selenate is the least reduced, followed by selenite, and elemental selenium;
selenide is even more reduced than elemental selenium. The
valence
Valence or valency may refer to:
Science
* Valence (chemistry), a measure of an element's combining power with other atoms
* Degree (graph theory), also called the valency of a vertex in graph theory
* Valency (linguistics), aspect of verbs rel ...
state is an important factor to the
toxicity of selenium. Selenate is the form required by organisms that need selenium as a
micronutrient
Micronutrients are nutrient, essential dietary elements required by organisms in varying quantities throughout life to orchestrate a range of physiological functions to maintain health. Micronutrient requirements differ between organisms; for exam ...
. These organisms have the ability to acquire, metabolize and excrete selenium. The level at which selenium becomes toxic varies from species to species and is related to other environmental factors like
pH and
alkalinity that influence the concentration of selenite over selenate.
Selenate and other forms of selenium are highest in areas where ancient seas have evaporated. These areas are enriched in selenium and over millennia, biologic adaptation has occurred.
References
Selenium(VI) compounds
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