حمض التلوريك

حمض التلوريك

الأسماء
اسم أيوپاك Hexahydroxidotellurium
أسماء أخرى Orthotelluric acid, Tellurium(VI) hydroxide
Identifiers
رقم CAS
3D model (JSmol)	Interactive image
ChEBI	CHEBI:30463 Y
ChemSpider	55517 Y
ECHA InfoCard	100.029.334
PubChem CID	62686
UNII	WE1KZR49WU Y
CompTox Dashboard (EPA)	DTXSID5064887
InChI	InChI={{{value}}}
SMILES
الخصائص
الصيغة الجزيئية	Te(OH) 6
كتلة مولية	229.64 g/mol
المظهر	White monoclinic crystals
الكثافة	3.07 g/cm3
نقطة الانصهار
قابلية الذوبان في الماء	50.1 g/100 ml at 30 °C
الحموضة (pKa)	7.68, 11.0 at 18 °C
البنية
الشكل الجزيئي	octahedral
Dipole moment	0 D
المخاطر
خطر رئيسي	corrosive
مركبات ذا علاقة
أنيونات أخرى	Hydrotelluric acid Tellurous acid Hydrogen telluride
مركـّبات ذات علاقة	Teflic acid Sulfuric acid Selenic acid
ما لم يُذكر غير ذلك، البيانات المعطاة للمواد في حالاتهم العيارية (عند 25 °س [77 °ف]، 100 kPa).
N verify (what is YN ?)
مراجع الجدول

حمض التلوريك Telluric acid هو مركب كيميائي صيغته Te(OH)
6. وهو صلب أبيض معمول من جزيئات Te(OH)
6 ثمانية الأسطح which persist in aqueous solution. There are two forms, rhombohedral and monoclinic, and both contain octahedral Te(OH)
6 molecules. Telluric acid is a weak acid which is dibasic, forming tellurate salts with strong bases and hydrogen tellurate salts with weaker bases or upon hydrolysis of tellurates in water. It is used as tellurium-source in the synthesis of oxidation catalysts.

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 التحضير

Telluric acid is formed by the oxidation of tellurium or tellurium dioxide with a powerful oxidising agent such as hydrogen peroxide, chromium trioxide or sodium peroxide.

TeO
2 + H
2O
2 + 2 H
2O → Te(OH)
6

Crystallization of telluric acid solutions below 10 °C gives Te(OH)
6·4H₂O. It is oxidizing, as shown by the electrode potential for the reaction below, although it is kinetically slow in its oxidations.

H
6TeO
6 + 2 H+
+ 2 e−
⇌ TeO
2 + 4 H
2O, E^o = +1.02 V

Chlorine, by comparison, is +1.36 V and selenous acid is +0.74 V in oxidizing conditions.

 الخصائص والتفاعلات

The anhydrous acid is stable in air at 100 °C but above this it dehydrates to form polymetatelluric acid, a white hygroscopic powder (approximate composition (H
2TeO
4)
10), and allotelluric acid, an acid syrup of unknown structure (approximate composition (H
2TeO
4)
3(H
2O)
4).

Typical salts of the acid contains the anions [Te(O)(OH)
5]−
and [Te(O)
2(OH)
4]²⁻. The presence of the tellurate ion TeO2−
4 has been confirmed in the solid state structure of Rb
6[TeO
5][TeO
4]. Strong heating at over 300 °C produces the α crystalline modification of tellurium trioxide, α-TeO
3. Reaction with diazomethane gives the hexamethyl ester, Te(OCH
3)
6.

Telluric acid and its salts mostly contain hexacoordinate tellurium. This is true even for salts such as magnesium tellurate, MgTeO
4, which is isostructural with magnesium molybdate and contains TeO
6 octahedra.

 أشكال أخرى من حمض التلوريك

Metatelluric acid, H
2TeO
4, the tellurium analogue of sulfuric acid, H
2SO
4, is unknown. Allotelluric acid of approximate composition (H
2TeO
4)
3(H
2O)
4, is not well characterised and may be a mixture of Te(OH)
6 and (H
2TeO
4)
n.

 أحماض التلوريوم الأخرى

Tellurous acid H
2TeO
3, containing tellurium in its +4 oxidation state, is known but not well characterised. Hydrogen telluride is an unstable gas that forms hydrotelluric acid upon addition to water.