sodium tellurite
{{chembox
| Verifiedfields = changed
| Watchedfields = changed
| verifiedrevid = 464404356
| Name = Sodium tellurite
| ImageFile1 = Sodium tellurite 2.jpg
| ImageSize1 = 250px
| ImageFile2 = Na2TeO3.png
| ImageSize2 = 250px
| ImageName =
| IUPACName =
| OtherNames = Sodium Tellurite IV, Tellurous acid disodium salt
|Section1={{Chembox Identifiers
| CASNo_Ref = {{cascite|changed|??}}
| CASNo = 10102-20-2
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| ChemSpiderID = 23309
| EINECS = 233-268-4
| PubChem = 24935
| RTECS = WY2450000
| UNNumber = 3288
| UNII_Ref = {{fdacite|correct|FDA}}
| UNII = 0BB57LA23Y
| InChI = 1/2Na.H2O3Te/c;;1-4(2)3/h;;(H2,1,2,3)/q2*+1;/p-2
| InChIKey = VOADVZVYWFSHSM-NUQVWONBAS
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| StdInChI = 1S/2Na.H2O3Te/c;;1-4(2)3/h;;(H2,1,2,3)/q2*+1;/p-2
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| StdInChIKey = VOADVZVYWFSHSM-UHFFFAOYSA-L
| SMILES = [Na+].[Na+].[O-][Te]([O-])=O
}}
|Section2={{Chembox Properties
| Formula = Na2TeO3
| MolarMass = 221.57774 g/mol
| Appearance = white crystals, powder
| Density = 6.245 g/cm3
| Solubility = soluble
greater than or equal to 100 mg/mL at 68°F
| MeltingPtC = 710
| BoilingPt =
| pKa =
| pKb =
}}
|Section3={{Chembox Structure
| MolShape =
| Coordination =
| CrystalStruct = rhombic
| Dipole =
}}
|Section7={{Chembox Hazards
| ExternalSDS =
| MainHazards =
| FlashPt =
| GHSPictograms = {{GHS06}}
| GHSSignalWord = Danger
| HPhrases = {{H-phrases|300|301|311|330|331}}
| PPhrases = {{P-phrases|260|261|264|270|271|280|284|301+310|302+352|304+340|310|311|312|320|321|322|330|361|363|403+233|405|501}}
| LD50 = 83 mg/kg (rat, oral)
}}
|Section8={{Chembox Related
| OtherAnions =
| OtherCations =
| OtherCompounds =
}}
}}
{{distinguish|Sodium telluride}}
Sodium tellurite is an inorganic tellurium compound with formula Na2TeO3. It is a water-soluble white solid and a weak reducing agent. Sodium tellurite is an intermediate in the extraction of the element, tellurium; it is a product obtained from anode slimes and is a precursor to tellurium.
Preparation
The main source of tellurium is from copper anode slimes, which contain precious metals as well as various tellurides. These slimes are roasted with sodium carbonate and oxygen to produce sodium tellurite.{{cite book|title = Inorganic chemistry|first1 = Egon|last1 = Wiberg|first2 = Arnold Frederick|last2 = Holleman|editor = Nils Wiberg|others = translated by Mary Eagleson|publisher = Academic Press|year = 2001|isbn = 0-12-352651-5|page = 588 }}
:Ag2Te + Na2CO3 + O2 → 2Ag + Na2TeO3 + CO2 (400–500 °C)
This is a reaction with silver telluride. The telluride is oxidized to tellurite and the silver(I) is reduced to silver.
Purification
The electrolysis of a tellurite solution yields purified tellurium.
:Anode: 4OH− → 2H2O + O2 + 4e−
:Cathode: TeO32− + 3H2O + 4e− → Te + 6OH−
Structure and properties
Tellurium has properties similar to sulfur and selenium. In the anhydrous form Na2TeO3 the tellurium atoms are 6 coordinate, three Te-O at 1.87 Å and three at 2.9 Å, with distorted octahedra sharing edges.{{cite journal|last1=Masse|first1=R.|last2=Guitel|first2=J.C.|last3=Tordjman|first3=I.|title=Preparation chimique et structure cristalline des tellurites de sodium et d'argent: Na2TeO3, Ag2TeO3|journal=Materials Research Bulletin|volume=15|issue=4|year=1980|pages=431–436|issn=0025-5408|doi=10.1016/0025-5408(80)90048-3}} In the pentahydrate, Na2TeO3.5H2O there are discrete tellurite anions, TeO32− which are pyramidal. The Te-O distance is 1.85 - 1.86 Å and the O-Te-O angle is close to 99.5°.{{cite journal | journal = Acta Crystallogr. B | title = Etude cristallographique du tellurite de sodium à cinq molécules d'eau, Na2TeIVO3·5H2O | volume = 35 | year = 1979 | pages = 1337–1340 | doi = 10.1107/S0567740879006403}} The tellurite anion is a weak base. Sodium tellurite would be similar to sodium selenite and sodium sulfite. Sodium tellurite is both a weak oxidizing agent and a weak reducing agent.
Applications
Sodium tellurite improves the corrosion resistance of electroplated nickel layers. Solutions of sodium tellurite are used for black or blue-black coatings on iron, steel, aluminum, and copper. In microbiology, sodium tellurite can be added to the growth medium to isolate bacteria with an inherent physiological resistance to its toxicity.Borsetti, Francesca; Toninello, Antonio; Zannoni, Davide (2003). "Tellurite uptake by cells of the facultative phototroph Rhodobacter capsulatus is a pH-dependent process." Federation of European Biochemical Societies. Volume 554, Issue 3, 20 November 2003, pp. 315–318. Elsevier B.V. {{doi|10.1016/S0014-5793(03)01180-3}}
References
{{reflist}}
- Cameo Chemicals. Sodium Tellurite. Retrieved March 8, 2009. Website: http://cameochemical.noaa.gov/chemical/5185{{Dead link|date=August 2023 |bot=InternetArchiveBot |fix-attempted=yes }}.
- {{Ullmann's | author = Knockaert, Guy | title = Tellurium and Tellurium Compounds | doi = 10.1002/14356007.a26_177.pub2 | year = 2002}}
{{Sodium compounds}}
{{Tellurites}}