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Topic summary

Hydroiodic acid

Hydroiodic acid
Names Other names
  • Aqueous hydrogen iodide
  • Hydriodic acid
  • Hydrogen iodide, hydrous
  • Hydronium iodide
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
EC Number
  • 233-109-9
RTECS number
  • MW3760000
UNII
  • InChI=1S/BrH/h1H
    Key: CPELXLSAUQHCOX-UHFFFAOYSA-N
  • InChI=1/BrH/h1H
    Key: CPELXLSAUQHCOX-UHFFFAOYAZ
  • [OH3+].[I-]
Properties HI(aq) Molar mass127.912 g·mol (HI) Appearance colorless liquid when pure, darkens on exposure to oxygen Odoracrid Density1.70 g/mL, azeotrope
(57% HI by weight) Boiling point127 °C (261 °F; 400 K) 1.03 bar, azeotrope Aqueous solution Acidity (pKa) −9.3 (HI) Hazards GHS labelling: DangerH314P260, P264, P280, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P310, P321, P363, P405, P501NFPA 704 (fire diamond)
3
0
0
ACID
Flash pointNon-flammable Related compounds
Other anions
Related compounds
Hydrogen iodide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Hydroiodic acid (or hydriodic acid) is a colorless aqueous solution of hydrogen iodide. It is a strong acid, in which hydrogen iodide is ionized completely into hydronium and iodide. Concentrated aqueous solutions of hydrogen iodide are usually 48% to 57% HI by mass.

Wikipedia source