Crystal structure
__ V 5+      __ O 2−
General
other names
Ratio formula V 2 O 5
Brief description

yellow to red-brown, odorless solid

External identifiers / databases
 CAS number 1314-62-1 EC number 215-239-8 ECHA InfoCard 100,013,855 PubChem 14814 ChemSpider 14130 Wikidata Q409173
properties
Molar mass 181.88 g mol −1
Physical state

firmly

density

3.36 g cm −3

Melting point

690 ° C

boiling point

1750 ° C (decomposition)

solubility
• poorly soluble in water
• considerably soluble in alkalis, acids and ethanol
safety instructions
GHS hazard labeling from  Regulation (EC) No. 1272/2008 (CLP) , expanded if necessary

danger

H and P phrases H: 302 + 332-318-335-341-361d-372-411
P: 261-273-280-305 + 351 + 338-314
MAK

Switzerland: 0.05 mg m −3 (measured as respirable dust )

Toxicological data

10 mg kg −1 ( LD 50ratoral )

As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Vanadium (V) oxide ( vanadium pentoxide ) is the most stable vanadium compound with the element oxygen .

presentation

Vanadium (V) oxide can be generated directly from the elements.

${\ displaystyle \ mathrm {4 \ V _ {(s)} + 5 \ O_ {2} \ rightarrow 2 \ V_ {2} O_ {5}}}$; ${\ displaystyle \ triangle H_ {B} = - 1560 \ \ mathrm {kJ / mol}}$

It can also be produced by annealing ammonium metavanadate (NH 4 VO 3 ) at 500–550 ° C in air.

${\ displaystyle {\ ce {2 NH4VO3 -> V2O5 + 2 NH3 + H2O}}}$

Since the thermal decomposition of ammonium metavanadate in air always produces slightly contaminated oxide, a major detour is accepted when the high-purity compound is necessary in order to obtain an exactly stoichiometric product. For this purpose, technical ammonium metavanadate is first incinerated in the oxygen stream to form the oxide, this is then converted to vanadium (V) oxide trichloride by means of thionyl chloride , hydrolyzed, converted with ammonia to a high-purity ammonium metavanadate and the same is finally burned again in the oxygen stream to form the oxide:

${\ displaystyle {\ ce {V2O5 + 3 SOCl2 -> 2 VOCl3 + 3 SO2}}}$
${\ displaystyle {\ ce {2 VOCl3 + 2 HNO3 -> [H_2O] [] V2O5 + 3 Cl2 + 2 NO + H2O}}}$
${\ displaystyle {\ ce {V2O5 + 2 NH3 + H2O -> 2 NH4VO3}}}$
${\ displaystyle {\ ce {2 NH4VO3 -> [T] [O_2] V2O5 + 2 NH3 + H2O}}}$

properties

Vanadium (V) oxide is a yellow to red-brown, odorless solid, in the crystal structure of which vanadium ions are located in the octahedral gaps of a densely packed sphere of oxygen ions. Each vanadium ion is surrounded by five oxygen ions, creating a distorted trigonal dipyramid. The crystal structure is orthorhombic , space group Pmn 2 1 (space group no. 31) , with the lattice parameters a = 11.54 Å , b = 4.383 Å and c = 3.571 Å.

use

Vanadium (V) oxide is used as a catalyst in the production of sulfuric acid using the contact process. It is also used in the manufacture of steel alloys such as ferrovanadium . Among other things, it is used as a catalyst in flue gas cleaning in waste incineration plants and to lower the melting point in enamel production.

Vanadium (V) oxide is also used to make white glass more impervious to UV light . To do this, it is added to the molten glass, the finished glass is not coated on the outside or inside. Bottles made from this glass are mainly used for beer to avoid the light taste.

Nanostructured vanadium (V) oxide, in combination with water, forms a composite material called "ceramic paper". This "ceramic paper" has excellent mechanical properties and is electrically conductive. Possible areas of application are therefore batteries, gas sensors and artificial muscles.

literature

• H. Oppermann, W. Brückner, W. Reichelt, E. Wolf, JI Terukow, FA Tschudnowski: Vanadium oxides . Akademie-Verlag, Berlin 1983.

Individual evidence

1. Entry on vanadium (V) oxide in the GESTIS substance database of the IFA , accessed on July 23, 2016(JavaScript required) .
2. a b Georg Brauer (Ed.) U. a .: Handbook of Preparative Inorganic Chemistry. 3rd, revised edition. Volume III, Ferdinand Enke, Stuttgart 1981, ISBN 3-432-87823-0 , p. 1422.
3. Entry on divanadium pentaoxide in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .
4. Swiss Accident Insurance Fund (Suva): Limit values ​​- current MAK and BAT values (search for 1314-62-1 or vanadium (V) oxide ), accessed on November 2, 2015.
5. Bertold Reuter and Jorg Jaskowsky: Vanadium (V) oxide, very pure . In: S. Young Tyree, Jr. (Ed.): Inorganic Syntheses . tape 9 . McGraw-Hill Book Company, Inc., 1967, p. 80-83 (English).
6. V. Shklover, T. Haibach, F. Ried, R. Nesper, P. Novak: Crystal structure of the product of Mg 2 + insertion into V 2 O 5 single crystals. In: Journal of Solid State Chemistry , 123, 1996, pp. 317-323, doi: 10.1006 / jssc.1996.0186 .
7. ^ Max Planck Society, Munich: Ceramics for Folding , accessed on April 11, 2013.