Tellurium trioxide
Tellurium trioxide (TeO3) is an inorganic chemical compound of tellurium and oxygen. In this compound, tellurium is in the +6 oxidation state.
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 tellurium(VI) oxide  | |
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| ECHA InfoCard | 100.033.277 | 
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| Properties | |
| TeO3 | |
| Molar mass | 175.6 g/mol | 
| Appearance | yellow-orange crystals (α-TeO3) | 
| Density | 5.07 g/cm3, solid | 
| Melting point | 430 °C (806 °F; 703 K) | 
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). 
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Polymorphs
    
There are two forms, yellow-red α-TeO3 and grey, rhombohedral, β-TeO3 which is less reactive.[1]
α-TeO3 has a structure similar to FeF3 with octahedral TeO6 units that share all vertices.[2]
Preparation
    
α-TeO3 can be prepared by heating orthotelluric acid, Te(OH)6, at over 300 °C.[1]  The β-TeO3  form can be prepared by heating α-TeO3  in a sealed tube with O2 and H2SO4.
α-TeO3 is unreactive to water but is a powerful oxidising agent when heated.[2] With alkalis it forms tellurates.[2]
α-TeO3 when heated loses oxygen to form firstly Te2O5  and then TeO2.[1]
References
    
- Inorganic Chemistry,Egon Wiberg, Arnold Frederick Holleman Elsevier 2001 ISBN 0-12-352651-5
 - Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
 
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