Sodium selenite

Sodium selenite

Sodium selenite
ATC code A12
ChemSpider  Y
EC number 233-267-9
Jmol-3D images Image
RTECS number VS7350000
UN number 2630
Molar mass 172.95 g·mol−1
Appearance colourless solid
Density 3.1 g/cm3
Melting point decomposes at 710 °C
85 g/100 mL (20 °C)
Solubility insoluble in alcohol, ethanol
Safety data sheet ICSC 0698
Very toxic (T+)
Dangerous for the environment (N)
R-phrases R51/53
S-phrases (S1/2), S28, S36/37, S45, S61
NFPA 704
Related compounds
Related compounds
Sodium sulfite
Sodium selenate
Sodium selenide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
 N  (: Y/N?)

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


  • Synthesis and fundamental reactions 1
  • Applications 2
  • Safety 3
  • See also 4
  • References 5
  • External links 6

Synthesis and fundamental reactions

Sodium selenite usually is prepared by the reaction of selenium dioxide with sodium hydroxide:[1]

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 SeO32−.[2] Oxidation of this anion gives sodium selenate, Na2SeO4.


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.[3]

Because selenium is an essential element, sodium selenite is an ingredient in some food supplements.

The US

  • Linus Pauling Institute page on selenium

External links

  1. ^ F. Féher, "Sodium Selenite" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 432.
  2. ^ Wickleder, Mathias S. (2002). "Sodium selenite, Na2SeO3". Acta Crystallographica Section E Structure Reports Online 58 (11): i103–i104.  
  3. ^ Bernd E. Langner "Selenium and Selenium Compounds" in Ullmann's Encyclopedia of Industrial Chemistry (published on-line in 2000) Wiley-VCH, Weinheim, 2002 doi:10.1002/14356007.a23_525
  4. ^ Schrauzer, GN (2001). "Nutritional selenium supplements: product types, quality, and safety". Journal of the American College of Nutrition 20 (1): 1–4.  
  5. ^ Wilber, C. G. (1980). "Toxicology of selenium". Clinical Toxicology (Free full text (see p. 211)) 17 (2): 171–230.  


See also

Selenium is toxic in high concentrations. The chronic toxic dose for human beings is about 2.4 to 3 milligrams of selenium per day.[5]