Iodine pentoxide

Summary

Iodine pentoxide is the chemical compound with the formula I2O5. This iodine oxide is the anhydride of iodic acid, and the only stable oxide of iodine. It is produced by dehydrating iodic acid at 200 °C in a stream of dry air:[1]

Iodine pentoxide
Names
IUPAC name
Iodine pentoxide
Other names
Iodine(V) oxide
Iodic anhydride
Identifiers
  • 12029-98-0 checkY
3D model (JSmol)
  • Interactive image
ChEBI
  • CHEBI:29914 checkY
ChemSpider
  • 140179 checkY
ECHA InfoCard 100.031.569 Edit this at Wikidata
  • 159402
UNII
  • UPU35C0Q0N checkY
  • DTXSID40923305 Edit this at Wikidata
  • InChI=1S/I2O5/c3-1(4)7-2(5)6 checkY
    Key: BIZCJSDBWZTASZ-UHFFFAOYSA-N checkY
  • InChI=1/I2O5/c3-1(4)7-2(5)6
    Key: BIZCJSDBWZTASZ-UHFFFAOYAR
  • O=I(=O)OI(=O)=O
Properties
I
2
O
5
Molar mass 333.81 g/mol
Appearance white crystalline solid[1]
hygroscopic
Density 4.980 g/cm3[1]
Melting point 300 °C (572 °F; 573 K)[2] (decomposes)
Solubility soluble in water and nitric acid;
insoluble in ethanol, ether and CS2
−79.4·10−6 cm3/mol
Thermochemistry
-173.0 kJ/mol
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
oxidizer
NFPA 704 (fire diamond)
Related compounds
Other anions
iodine pentafluoride
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
Iodine pentoxide
Fresh iodine pentoxide
2HIO3 → I2O5 + H2O

Structure edit

I2O5 is bent with an I–O–I angle of 139.2°, but the molecule has no mirror plane so its symmetry is C2 rather than C2v. The terminal I–O distances are around 1.80 Å and the bridging I–O distances are around 1.95 Å.[3]

Reactions edit

Iodine pentoxide easily oxidises carbon monoxide to carbon dioxide at room temperature:

5 CO + I2O5I2 + 5 CO2

This reaction can be used to analyze the concentration of CO in a gaseous sample.

I2O5 forms iodyl salts, [IO2+], with SO3 and S2O6F2, but iodosyl salts, [IO+], with concentrated sulfuric acid.

Iodine pentoxide decomposes to iodine (vapor) and oxygen when heated to about 350 °C.[4]

References edit

  1. ^ a b c Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. pp. 851–852. ISBN 978-0-08-037941-8.
  2. ^ Patnaik, P. (2002). Handbook of Inorganic Chemicals. McGraw-Hill. ISBN 0-07-049439-8.
  3. ^ Selte, K.; Kjekshus, A. (1970). "Iodine Oxides: Part III. The Crystal Structure of I2O5" (PDF). Acta Chemica Scandinavica. 24 (6): 1912–1924. doi:10.3891/acta.chem.scand.24-1912.
  4. ^ G. Baxter and G. Tilley, "A Revision of the Atomic Weights of Iodine and Silver," The Chemical News and Journal of Industrial Science; Volumes 99-100, Royal Society Anniversary Meeting, December 3, 1909, p. 276. (Google Books)