Potassium biiodate

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Potassium biiodate
IUPAC name potassium µ-hydridobis(trioxidoiodate)(1−)
Other names potassium hydrogen iodate
Identifiers
InChI InChI=1/2HIO3.K/c2*2-1(3)4;/h2*(H,2,3,4);/q;;+1/p-1
InChIKey ACAYDTMSDROWHW-REWHXWOFAC
Standard InChI InChI=1S/2HIO3.K/c2*2-1(3)4;/h2*(H,2,3,4);/q;;+1/p-1
Standard InChIKey ACAYDTMSDROWHW-UHFFFAOYSA-M
CAS number [13455-24-8]
EC number 236-650-9
ChemSpider 2341255
Properties[1]
Chemical formula KH(IO3)2
Molar mass 389.91 g mol−1
Appearance white crystals
Solubility in water 1.33 g/100 ml (15 °C)
Hazards[2][3][Note 1]
EU index number not listed
GHS pictograms Skin Corr. 1C, Eye Dam. 1Ox. Sol. 2Acute Tox. 4 (oral)
GHS signal word DANGER
GHS hazard statements H272, H302, H314, H318
GHS precautionary statements P210, P220, P221, P260, P264, P270, P280, P301+312, P301+330+331, P303+361+353, P363, P304+340, P310, P321
Flash point Non-flammable
Related compounds
Other compounds Potassium iodate
Iodic acid
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)

Potassium biiodate, KH(IO3)2, is a primary standard strong acid in analytical chemistry.[4][5]

Chemistry

The biiodate anion is a hydrogen-bonded species formed from the reaction of an iodate anion with undissociated iodic acid.[6]

IO3 + HIO3 → [H(IO3)2]     Kc ≈ 4 dm3 mol−1

Ferroelectricity

Potassium biiodate forms a ferroelectric phase below the Curie point of TC = 223(2) K.[7] The second-order phase transition appears to be associated with the ordering of the hydrogen bonds in the crystal structure.[8]

Notes and references

Notes

  1. Hazards were assessed as for an equimolar mixture of potassium iodate and iodic acid.

References

  1. CRC Handbook of Chemistry and Physics, 62nd ed.; Weast, Robert C., Ed.; CRC Press: Boca Raton, FL, 1981; p B-133. ISBN 0-8493-0462-8.
  2. HSNO Chemical Classification Information Database, <http://www.ermanz.govt.nz/Chemicals/ChemicalDisplay.aspx?SubstanceID=1913> (accessed 9 September 2010), New Zealand Environmental Risk Management Authority. (potassium iodate)
  3. HSNO Chemical Classification Information Database, <http://www.ermanz.govt.nz/Chemicals/ChemicalDisplay.aspx?SubstanceID=12620> (accessed 9 September 2010), New Zealand Environmental Risk Management Authority. (iodic acid)
  4. Kolthoff, I. M.; van Berk, L. H. The Use of Potassium Bi-iodate as a Standard Substance in Alkalimetric and Iodimetric Titrations. J. Am. Chem. Soc. 1926, 48 (11), 2799–2801. DOI: 10.1021/ja01690a006.
  5. Processing KODAK Motion Picture Films, Module 4 – Potassium Biiodate; Kodak, <http://motion.kodak.com/motion/uploadedFiles/US_plugins_acrobat_en_motion_support_processing_h244_potBiiod.pdf>. (accessed 9 September 2010).
  6. Greenwood, Norman N.; Earnshaw, A. Chemistry of the Elements; Pergamon: Oxford, 1984; p 1010. ISBN 0-08-022057-6.
  7. Petrosyana, A. M.; Buscha, A. A.; Chechkina, V. V.; Volkova, A. F.; Venevtsev, Yu. N. Ferroelectric phase transition in potassium Bi-iodate. Ferroelectrics 1978, 21 (1), 525–26. DOI: 10.1080/00150197808237316.
  8. Barabash, A.; Baran, J.; Gavrilko, T.; Eshimov, K.; Puchkovskaya, G.; Ratajczak, H. Structure and dynamics of crystal α-modification of potassium biiodate. J. Mol. Struct. 1997, 404 (1–2), 187–91. DOI: 10.1016/S0022-2860(96)09380-5.