 | This articleis missing information about the biological actions of the compound. Please expand the article to include this information. Further details may exist on thetalk page.(September 2024) |
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| Identifiers | |
|---|---|
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3D model (JSmol) | |
| ChEBI | |
| ChEMBL | |
| ChemSpider |
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| ECHA InfoCard | 100.030.230 |
| EC Number |
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| KEGG |
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| RTECS number |
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| UNII |
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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) | |
Lattice volume (V) | 1676.70 Å3 (pentahydrate) |
Formula units (Z) | 8 (pentahydrate) |
| Pharmacology | |
| A12CE02 (WHO) (Oral),B05XA20 (WHO) (Parenteral) | |
| Hazards | |
| GHS labelling:[1] | |
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| Danger | |
| H300+H330,H315,H317,H319,H411 | |
| P260,P264,P270,P271,P272,P273,P280,P284,P301+P310+P330,P302+P352,P304+P340+P310,P305+P351+P338,P333+P313,P337+P313,P362,P391,P403+P233,P405,P501 | |
| NFPA 704 (fire diamond) | |
| > 400 °C (752 °F; 673 K)[1] | |
Threshold limit value (TLV) | 0.2 mg/m3 (as selenium)[4] (TWA) |
| Lethal dose or concentration (LD, LC): | |
LD50 (median dose) | 7 mg/kg (oral, rat)[2] |
LDLo (lowest published) | 3.3 mg/kg (oral, sheep)[4] |
| NIOSH (US health exposure limits):[4] | |
PEL (Permissible) | 0.2 mg/m3 (TWA, as selenium) |
REL (Recommended) | 0.2 mg/m3 (TWA, as selenium) |
IDLH (Immediate danger) | 1 mg/m3 |
| Related compounds | |
Otheranions | |
Othercations | |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Sodium selenite is theinorganic compound with the formulaNa2SeO3. Thissalt is a colourless solid. The pink coloured pentahydrateNa2SeO3·5H2O is the most common water-solubleselenium compound.
Sodium selenite usually is prepared by the reaction ofselenium dioxide withsodium hydroxide:[5]
The hydrate converts to the anhydrous salt upon heating to 40 °C (104 °F).
According toX-ray crystallography, both anhydrousNa2SeO3 and its pentahydrate feature pyramidalSeO2−3. TheSe−O distances range from1.67 to 1.72 Å.[6] Oxidation of this anion givessodium selenate,Na2SeO4.[3]
Together with the relatedbarium andzincselenites, sodium selenite is mainly used in the manufacture of colorlessglass. The pink color imparted by these selenites cancels out the green color imparted byiron impurities.[7]
Because selenium is anessential element, sodium selenite is an ingredient indietary supplements such as multi-vitamin/mineral products, but supplements that provide only selenium use L-selenomethionine or aselenium-enriched yeast.
The USFood 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 effectivesuicide agent.[9]
Selenium is toxic in high concentrations. As sodium selenite, thechronic toxic dose for human beings was described as about2.4 to 3 mg of selenium per day.[10] In 2000, the USInstitute of Medicine set the adultTolerable upper intake levels (UL) for selenium from all sources - food, drinking water and dietary supplements - at400 μg/d.[11] TheEuropean Food Safety Authority reviewed the same safety question and set its UL at300 μg/d.[12]
