Chemistry:Hydrogen telluride

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Hydrogen telluride
Hydrogen telluride.png
Liquid hydrogen telluride in a test tube
Structural diagram of the hydrogen telluride molecule
Space-filling model of the hydrogen telluride molecule
  Tellurium, Te
  Hydrogen, H
Names
IUPAC name
hydrogen telluride
Other names
hydrotelluric acid
tellane
tellurium hydride
dihydrogen telluride
tellurane
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
EC Number
  • 236-813-4
UNII
Properties
H2Te
Molar mass 129.6158 g mol−1
Appearance colourless gas
Odor Pungent, resembles rotting garlic or leeks
Density 3.310 g/L, gas
2.57 g/cm3 (−20 °C, liquid)
Melting point −49 °C (−56 °F; 224 K)[1]
Boiling point −2.2 °C (28.0 °F; 270.9 K) (unstable above −2 °C)
0.70 g/100 mL
Acidity (pKa) 2.6
Conjugate acid Telluronium
Conjugate base Telluride
Structure
bent
Thermochemistry
0.7684 kJ/g
Hazards
Main hazards toxic
NFPA 704 (fire diamond)
Flammability code 4: Will rapidly or completely vaporize at normal atmospheric pressure and temperature, or is readily dispersed in air and will burn readily. Flash point below 23 °C (73 °F). E.g. propaneHealth code 4: Very short exposure could cause death or major residual injury. E.g. VX gasReactivity code 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g. calciumSpecial hazards (white): no codeNFPA 704 four-colored diamond
4
4
1
Related compounds
Other anions
 H2O
H2S
H2Se
H2Po
Other cations
 Na2Te
Ag2Te
K2Te
Rb2Te
Cs2Te
Related compounds
 telluric acid
tellurous acid
stibine
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references
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Hydrogen telluride is the inorganic compound with the formula H2Te. A hydrogen chalcogenide and the simplest hydride of tellurium, it is a colorless gas. Although unstable in ambient air, the gas can exist at very low concentrations long enough to be readily detected by the odour of rotting garlic at extremely low concentrations; or by the revolting odour of rotting leeks at somewhat higher concentrations. Most compounds with Te–H bonds (tellurols) are unstable with respect to loss of H2. H2Te is chemically and structurally similar to hydrogen selenide, both are acidic. The H–Te–H angle is about 90°. Volatile tellurium compounds often have unpleasant odours, reminiscent of decayed leeks or garlic.[2]

Synthesis

Electrolytic methods have been developed.[3]

H2Te can also be prepared by hydrolysis of the telluride derivatives of electropositive metals.[4] The typical hydrolysis is that of aluminium telluride:

Al2Te3 + 6 H2O → 2 Al(OH)3 + 3 H2Te

Other salts of Te2− such as MgTe and sodium telluride can also be used. Na2Te can be made by the reaction of Na and Te in anhydrous ammonia.[5] The intermediate in the hydrolysis, HTe−, can be isolated as salts as well. NaHTe can be made by reducing tellurium with NaBH4.[5]

Hydrogen telluride cannot be efficiently prepared from its constituent elements, in contrast to H2Se.[3]

Properties

H2Te is an endothermic compound, degrading to the elements at room temperature:

H2Te → H2 + Te

Light accelerates the decomposition. It is unstable in air, being oxidized to water and elemental tellurium:[6]

2 H2Te + O2 → 2 H2O + 2 Te

It is almost as acidic as phosphoric acid (Ka = 8.1×10−3), having a Ka value of about 2.3×10−3.[6] It reacts with many metals to form tellurides.[7]

See also

References

  1. ↑ Lide, David R., ed (2006). CRC Handbook of Chemistry and Physics (87th ed.). Boca Raton, FL: CRC Press. ISBN 0-8493-0487-3. 
  2. ↑ Greenwood, N. N.; & Earnshaw, A. (1997). Chemistry of the Elements (2nd Edn.), Oxford:Butterworth-Heinemann. ISBN:0-7506-3365-4.
  3. ↑ 3.0 3.1 F. Fehér, "Hydrogen Telluride" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. pp. 438.
  4. ↑ Shriver, Atkins. Inorganic Chemistry, Fifth Edition. W. H. Freeman and Company, New York, 2010; pp 407.
  5. ↑ 5.0 5.1 Nicola Petragnani; Hélio A. Stefani (2007). Tellurium in organic synthesis. Best synthetic methods (2nd ed.). Academic Press. p. 6. ISBN 978-0-08-045310-1. 
  6. ↑ 6.0 6.1 Egon Wiberg; Arnold Frederick Holleman (2001). Nils Wiberg. ed. Inorganic chemistry. Academic Press. p. 589. ISBN 0-12-352651-5. 
  7. ↑ Henry Enfield Roscoe; Carl Schorlemmer (1878). A treatise on chemistry. 1. Appleton. pp. 367–368. 



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