|Molar mass||172.94 g·mol−1|
|Melting point||decomposes at 710 °C|
|85 g/100 mL (20 °C)|
|Solubility||insoluble in alcohol, ethanol|
|EU classification||Very toxic (T+)
Dangerous for the environment (N)
|R-phrases||R23, R28, R31, R43, R51/53|
|S-phrases||(S1/2), S28, S36/37, S45, S61|
Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
|what is: / ?)(|
Synthesis and fundamental reactions
- SeO2 + 2 NaOH → Na2SeO3 + H2O
The hydrate converts to the anhydrous salt upon heating to 40 °C.
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.
The US Food and Drug Administration approved a selenium supplement to animal diets, however 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.” 
- F. Féher, "Sodium Selenite" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 432.
- Wickleder, Mathias S. (2002). "Sodium selenite, Na2SeO3". Acta Crystallographica Section E Structure Reports Online 58 (11): i103–i104. doi:10.1107/S1600536802019384. ISSN 1600-5368.
- 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
- Schrauzer, GN (2001). "Nutritional selenium supplements: product types, quality, and safety". Journal of the American College of Nutrition 20 (1): 1–4. doi:10.1080/07315724.2001.10719007. PMID 11293463.
- Wilber, C. G. (1980). "Toxicology of selenium". Clinical Toxicology (FREE FULL TEXT (SEE P. 211)) 17 (2): 171–230. doi:10.3109/15563658008985076. PMID 6998645.