Chemistry:Sodium selenite
 | This article is missing information about the biological actions of the compound. (September 2024) |
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3D model (JSmol)
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PubChem CID
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| UN number | 2630 |
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| Properties | |
| Na2O3Se | |
| Molar mass | 172.948 g·mol−1 |
| Appearance | colourless solid |
| Density | 3.1 g/cm3 |
| Melting point | 350 °C (662 °F; 623 K)[2] (decomposes over 300 °C (572 °F; 573 K)) |
| 89.8 g/100mL (20 °C (68 °F; 293 K))[1] | |
| Vapor pressure | < 0.00133 hPa (1.93×10−5 psi) (20 °C (68 °F; 293 K))[1] |
| Structure[3] | |
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| Pbcm (pentahydrate) | |
a = 6.5865 Å, b = 17.2263 Å, c = 14.7778 Å (pentahydrate)
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Lattice volume (V)
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1676.70 Å3 (pentahydrate) |
Formula units (Z)
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8 (pentahydrate) |
| Pharmacology | |
| 1=ATC code }} | A12CE02 (WHO) (Oral), B05XA20 (WHO) (Parenteral) |
| Hazards | |
| GHS pictograms |   
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| GHS Signal word | Danger |
| H300+330Script error: No such module "Preview warning".Category:GHS errors, H315, H317, H319, H411 | |
| P260, P264, P270, P271, P272, P273, P280, P284, P301+310+330Script error: No such module "Preview warning".Category:GHS errors, P302+352, P304+340+310, P305+351+338, P333+313, P337+313, P362, P391, P403+233, P405, P501 | |
| NFPA 704 (fire diamond) | |
| > 400 °C (752 °F; 673 K)[1] | |
Threshold limit value (TLV)
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0.2 mg/m3 (as selenium)[4] (TWA) |
| Lethal dose or concentration (LD, LC): | |
LD50 (median dose)
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7 mg/kg (oral, rat)[2] |
LDLo (lowest published)
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3.3 mg/kg (oral, sheep)[4] |
| NIOSH (US health exposure limits):[4] | |
PEL (Permissible)
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0.2 mg/m3 (TWA, as selenium) |
REL (Recommended)
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0.2 mg/m3 (TWA, as selenium) |
IDLH (Immediate danger)
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1 mg/m3 |
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Other anions
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Other cations
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
 verify (what is   ?)
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| Infobox references | |
Sodium selenite is the inorganic compound with the formula Na
2SeO
3. This salt is a colourless solid. The pink coloured pentahydrate Na
2SeO
3 · 5H2O is the most common water-soluble selenium compound.
Synthesis and fundamental reactions
Sodium selenite usually is prepared by the reaction of selenium dioxide with sodium hydroxide:[5]
- SeO
2 + 2 NaOH → Na
2SeO
3 + H
2O
The hydrate is stable in moist air, and converts to the anhydrous salt upon heating to 40 °C (104 °F) or storage in moist air.[5]
According to X-ray crystallography, both anhydrous Na
2SeO
3 and its pentahydrate feature pyramidal SeO2−
3. The Se–O distances range from 1.67 to 1.72 Å.[6] Oxidation of this anion gives sodium selenate, Na
2SeO
4.[3]
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.[7]
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."[8]
Sodium selenite has been proposed as an effective suicide agent.[9]
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 mg of selenium per day.[10] In 2000, the US Institute of Medicine set the adult Tolerable upper intake levels (UL) for selenium from all sources - food, drinking water and dietary supplements - at 400 μg/d.[11] The European Food Safety Authority reviewed the same safety question and set its UL at 300 μg/d.[12]
See also
References
- ↑ 1.0 1.1 1.2 1.3 Sigma-Aldrich Co., Sodium selenite.
- ↑ 2.0 2.1 2.2 "SDS - Sodium selenite". ThermoFisher Scientific. 21 December 2025. p. 3. https://www.fishersci.com/store/msds?partNumber=AA1258522&productDescription=SOD+SELITE+ANHY+99MIN+TYP+100G&vendorId=VN00024248&countryCode=US&language=en.
- ↑ 3.0 3.1 Mereiter, Kurt (2013). "Sodium Selenite Pentahydrate, Na2SeO3·5H2O". Acta Crystallographica Section E 69 (11): i77–i78. doi:10.1107/S1600536813028602. PMID 24454013.
- ↑ 4.0 4.1 4.2 "Selenium compounds". Immediately Dangerous to Life and Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH). https://www.cdc.gov/niosh/idlh/7782492.html.
- ↑ 5.0 5.1 Féher, F. (1963). "7. Sulfur, Selenium, Tellurium - Sodium Selenite". in Brauer, G.. Handbook of Preparative Inorganic Chemistry. 1 (2nd ed.). New York, NY: Academic Press. p. 431-432. https://archive.org/details/Handbook_of_Preparative_Inorganic_Chemistry_1_2_Brauer/page/n455/mode/2up.
- ↑ Wickleder, Mathias S. (2002). "Sodium Selenite, Na2SeO3". Acta Crystallographica Section E 58 (11): i103–i104. doi:10.1107/S1600536802019384. ISSN 1600-5368. Bibcode: 2002AcCrE..58I.103W.
- ↑ Langner, Bernd E.. "Ullmann's Encyclopedia of Industrial Chemistry". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. 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.
- ↑ Nitschke, Philip; Stewart, Fiona (January 2021). The peaceful pill ehandbook. Bellingham, WA: Exit International. p. 192. ISBN 979-8-7396-5305-5.
- ↑ Wilber, C. G. (1980). "Toxicology of selenium". Clinical Toxicology 17 (2): 171–230. doi:10.3109/15563658008985076. PMID 6998645.
- ↑ Institute of Medicine (2000). "Selenium". Dietary Reference Intakes for Vitamin C, Vitamin E, Selenium, and Carotenoids. Washington, DC: The National Academies Press. pp. 284–324. doi:10.17226/9810. ISBN 978-0-309-06935-9. https://www.ncbi.nlm.nih.gov/books/NBK225470/.
- ↑ Tolerable Upper Intake Levels For Vitamins And Minerals, European Food Safety Authority, 2006, http://www.efsa.europa.eu/sites/default/files/efsa_rep/blobserver_assets/ndatolerableuil.pdf
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