Sodium selenite

src: en.jhadd.com

Sodium selenite is the inorganic compound with the formula Na₂SeO₃. This salt is a colourless solid. The pentahydrate Na₂SeO₃(H₂O)₅ is the most common water-soluble selenium compound.

Video Sodium selenite

Synthesis and fundamental reactions

Sodium selenite usually is prepared by the reaction of selenium dioxide with sodium hydroxide:

SeO₂ + 2 NaOH -> Na₂SeO₃ + H₂O

The hydrate converts to the anhydrous salt upon heating to 40 °C.

Akin to the related salt sodium sulfite, Na₂SeO₃ features a pyramidal dianion SeO₃^2-. Oxidation of this anion gives sodium selenate, Na₂SeO₄.

Maps Sodium selenite

Applications

Together with the related barium and zinc selenites, sodium selenite is mainly used in the manufacture of colorless glass. The pink color imparted by these selenites cancels out the green color imparted by iron impurities.

Because selenium is an essential element, sodium selenite is an ingredient in dietary supplements such as multi-vitamin/mineral products, but supplements that provide only selenium use L-selenomethionine or a selenium-enriched yeast.

The US Food and Drug Administration approved a selenium supplement to animal diets; the most common form is sodium selenite for pet foods. According to one article, "not much was known about which selenium compounds to approve for use in animal feeds when the decisions were made back in the 1970s .. At the time the regulatory action was taken, only the inorganic selenium salts (sodium selenite and sodium selenate) were available at a cost permitting their use in animal feed."

src: sc02.alicdn.com

Safety

Selenium is toxic in high concentrations. As sodium selenite, the chronic toxic dose for human beings was described as about 2.4 to 3 milligrams of selenium per day. In 2000, the U.S. Institute of Medicine set the adult Tolerable upper intake levels (UL) for selenium from all sources - food, drinking water and dietary supplements - at 400 ?g/day. The European Food Safety Authority reviewed the same safety question and set its UL at 300 ?g/day.

src: cdn.shopify.com

See also

• Selenite (ion)

src: sc01.alicdn.com

References

src: www.earthspick.com

External links

• Linus Pauling Institute page on selenium

Source of article : Wikipedia