Sodium selenite
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| Identifiers | |
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3D model (Jmol)
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| ChEBI | |
| ChemSpider | |
| ECHA InfoCard | 100.030.230 |
| EC Number | 233-267-9 |
| KEGG | |
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PubChem CID
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| RTECS number | VS7350000 |
| UNII | |
| UN number | 2630 |
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| Properties | |
| Na2O3Se | |
| 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 |
| Structure | |
| tetragonal | |
| Pharmacology | |
| A12CE02 (WHO) | |
| Hazards | |
| Safety data sheet | ICSC 0698 |
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EU classification (DSD)
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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 |
| NFPA 704 | |
| Related compounds | |
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Related compounds
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Sodium sulfite Sodium selenate Sodium selenide |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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 (what is   ?) |
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| Infobox references | |
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.
Sodium selenite usually is prepared by the reaction of selenium dioxide with sodium hydroxide:
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−. 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.
Because selenium is an essential element, sodium selenite is an ingredient in some food supplements.
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.”
Selenium is toxic in high concentrations. The chronic toxic dose for human beings is about 2.4 to 3 milligrams of selenium per day.
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Wikipedia