Perxenic Acid
Get Perxenic Acid essential facts below. View Videos or join the Perxenic Acid discussion. Add Perxenic Acid to your PopFlock.com topic list for future reference or share this resource on social media.
Perxenic Acid

In chemistry, perxenates are salts of the yellow[1] xenon-containing anion .[2] This anion has octahedral molecular geometry, as determined by Raman spectroscopy, having O-Xe-O bond angles varying between 87° and 93°.[3] The Xe-O bond length was determined by X-ray crystallography to be 1.875 Å.[4]

Synthesis

Perxenates are synthesized by the disproportionation of xenon trioxide when dissolved in strong alkali:[5]

2 XeO3 (s) + 4 OH- (aq) -> Xe (g) + (aq) + O2 (g) + 2 H2O (l)

When Ba(OH)2 is used as the alkali, barium perxenate can be crystallized from the resulting solution.[5]

Perxenic acid

Perxenic acid

Perxenic acid is the unstable conjugate acid of the perxenate anion, formed by the solution of xenon tetroxide in water. It has not been isolated as a free acid, because under acidic conditions it rapidly decomposes into xenon trioxide and oxygen gas:[6][7]

2 + 6 -> 2 + 4 +

Its extrapolated formula, H4XeO6, is inferred from the octahedral geometry of the perxenate ion in its alkali metal salts.[6][4]

The pKa of aqueous perxenic acid has been indirectly calculated to be below 0, making it an extremely strong acid. Its first ionization yields the anion , which has a pKa value of 4.29, still relatively acidic. The twice deprotonated species has a pKa value of 10.81.[8] Due to its rapid decomposition under acidic conditions as described above, however, it is most commonly known as perxenate salts, bearing the anion .[6][2]

Properties

Perxenic acid and the anion are both strong oxidizing agents,[9] capable of oxidising silver(I) to silver(III), copper(II) to copper(III),[10] and manganese(II) to permanganate.[11] The perxenate anion is unstable in acidic solutions,[10] being almost instantaneously reduced to .[1]

The sodium, potassium, and barium salts are soluble.[12] Barium perxenate solution is used as the starting material for the synthesis of xenon tetroxide (XeO4) by mixing it with concentrated sulfuric acid:[13]

Ba2XeO6 (s) + 2 H2SO4 (l) -> XeO4 (g) + 2 BaSO4 (s) + 2 H2O (l)

Most metal perxenates are stable, except silver perxenate, which decomposes violently.[10]

Applications

Sodium perxenate, Na4XeO6, can be used for the analytic separation of trace amounts of americium from curium. The separation involves the oxidation of Am3+ to Am4+ by sodium perxenate in acidic solution in the presence of La3+, followed by treatment with calcium fluoride, which forms insoluble fluorides with Cm3+ and La3+, but retains Am4+ and Pu4+ in solution as soluble fluorides.[9]

References

  1. ^ a b Cotton, F. Albert; Wilkinson, Geoffrey; Murillo, Carlos A.; Bochmann, Manfred (1999), Advanced Inorganic Chemistry (6th ed.), New York: Wiley-Interscience, p. 593, ISBN 0-471-19957-5
  2. ^ a b Holleman, Arnold Frederik; Wiberg, Egon (2001), Wiberg, Nils (ed.), Inorganic Chemistry, translated by Eagleson, Mary; Brewer, William, San Diego/Berlin: Academic Press/De Gruyter, p. 399, ISBN 0-12-352651-5
  3. ^ Peterson, J. L.; Claassen, H. H.; Appelman, E. H. (March 1970). "Vibrational spectra and structures of xenate(VI) and perxenate(VIII) ions in aqueous solution". Inorganic Chemistry. 9 (3): 619-621. doi:10.1021/ic50085a037.
  4. ^ a b Hamilton; Ibers, J.; MacKenzie, D. (Aug 1963). "Geometry of the Perxenate Ion". Science. 141 (3580): 532-534. Bibcode:1963Sci...141..532H. doi:10.1126/science.141.3580.532. ISSN 0036-8075. PMID 17738629.
  5. ^ a b Harding, Charlie; Johnson, David Arthur; Janes, Rob (2002). Elements of the p Block. Molecular World. 9. Royal Society of Chemistry. p. 93. ISBN 0-85404-690-9.
  6. ^ a b c Klaening, U. K.; Appelman, E. H. (October 1988). "Protolytic properties of perxenic acid". Inorganic Chemistry. 27 (21): 3760-3762. doi:10.1021/ic00294a018.
  7. ^ Holleman, Arnold Frederik; Wiberg, Egon (2001), Wiberg, Nils (ed.), Inorganic Chemistry, translated by Eagleson, Mary; Brewer, William, San Diego/Berlin: Academic Press/De Gruyter, p. 400, ISBN 0-12-352651-5
  8. ^ John H. Holloway; Eric G. Hope (1998). A. G. Sykes (ed.). Advances in Inorganic Chemistry. 46. Academic Press. p. 67. ISBN 0-12-023646-X.
  9. ^ a b Holcomb, H. P. (March 1965). "Analytical Oxidation of Americium with Sodium Perxenate". Analytical Chemistry. 37 (3): 415. doi:10.1021/ac60222a002.
  10. ^ a b c Allen J. Bard; Roger Parsons; Joseph Jordan; International Union of Pure and Applied Chemistry (1985). Standard Potentials in Aqueous Solution. CRC Press. p. 778. ISBN 0-8247-7291-1.
  11. ^ Linus Pauling (1988). General Chemistry (3rd ed.). Courier Dover Publications. p. 251. ISBN 0-486-65622-5.
  12. ^ Thomas Scott; Mary Eagleson (1994). Concise encyclopedia chemistry. Walter de Gruyter. p. 1183. ISBN 3-11-011451-8.
  13. ^ Charlie Harding; David Arthur Johnson; Rob Janes (2002). Elements of the p block. Great Britain: Royal Society of Chemistry. pp. 92-93. ISBN 0-85404-690-9.

  This article uses material from the Wikipedia page available here. It is released under the Creative Commons Attribution-Share-Alike License 3.0.

Perxenic_acid
 



 



 
Music Scenes