Tellurium dioxide
 |
|
 α-TeO2, paratellurite
|
|
| Names | |
|---|---|
| Other names
Tellurium(IV) oxide
|
|
| Identifiers | |
|
3D model (Jmol)
|
|
| ChemSpider | |
| ECHA InfoCard | 100.028.357 |
|
PubChem CID
|
|
| UNII | |
|
|
|
|
| Properties | |
| TeO2 | |
| Molar mass | 159.60 g/mol |
| Appearance | white solid |
| Density | 5.670 g/cm3(orthorhombic) 6.04 g/cm3 (tetragonal) |
| Melting point | 732 °C (1,350 °F; 1,005 K) |
| Boiling point | 1,245 °C (2,273 °F; 1,518 K) |
| negligible | |
| Solubility | soluble in acid and alkali |
|
Refractive index (nD)
|
2.24 |
| Hazards | |
| Flash point | Non-flammable |
| Related compounds | |
|
Other cations
|
Sulfur dioxide Selenium dioxide |
|
Tellurium trioxide Tellurium monoxide |
|
|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|
|
 (what is   ?) |
|
| Infobox references | |
Tellurium dioxide (TeO2) is a solid oxide of tellurium. It is encountered in two different forms, the yellow orthorhombic mineral tellurite, β-TeO2, and the synthetic, colourless tetragonal (paratellurite), α-TeO2. Most of the information regarding reaction chemistry has been obtained in studies involving paratellurite, α-TeO2.
Paratellurite, α-TeO2, is produced by reacting tellurium with O2:
An alternative preparation is to dehydrate tellurous acid, H2TeO3, or to thermally decompose basic tellurium nitrate,Te2O4.HNO3 above 400 °C.
The speed of sound in Tellurium dioxide is 4250 m/s.
TeO2 is barely soluble in water and soluble in strong acids and Alkali metal hydroxides. It is an amphoteric substance and therefore can act both as an acid or as a base depending on the solution it is in. It reacts with acids to make tellurium salts and bases to make tellurites. It can be oxidized to telluric acid or tellurates.
Paratellurite, α-TeO2, converts at high pressure into the β-, tellurite form. Both the α-, (paratellurite) and β- (tellurite forms) contain four coordinate Te with the oxygen atoms at four of the corners of a trigonal bipyramid. In paratellurite all vertices are shared to give a rutile-like structure, where the O-Te-O bond angle are 140°. α-TeO2 In tellurite pairs of trigonal pyramidal, TeO4 units, sharing an edge, share vertices to then form a layer. The shortest Te-Te distance in tellurite is 317 pm, compared to 374 pm in paratellurite. Similar Te2O6 units are found in the mineral denningite.
TeO
2 melts at 732.6 °C, forming a red liquid.
...
Wikipedia