Hydrogen compounds: hydrogen fluoride

hydrogen symbol icon

The hydrogen in hydrogen fluoride formally is in the oxidation state 1.

Crystal structure of hydrogen fluoride

Hydrogen fluoride

  • Formula as often written: HF
  • Hill system formula: F1H1
  • CAS registry number: [7664-39-3]
  • Formula weight: 20.006
  • Class: fluoride

Synonyms

  • hydrogen fluoride
  • hydrogen(I) fluoride
  • hydrofluoric acid

Physical properties

  • Colour: colourless
  • Appearance: gas
  • Melting point: -83.5°C
  • Boiling point: 19.5°C
  • Density: 1000 kg m-3 (liquid at 0°C)

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Element analysis

Element percentages for the elements in hydrogen fluoride
Element %
F 94.96
H 5.04

Synthesis

Dry hydrogen fluoride gas may be made in the laboratory by heating anhydrous potassium hydrogen fluoride and collecting the evolved hydrogen fluoride gas.

KHF2(s) (500°C) → HF(g) + KF(s)

Hydrogen fluoride gas may be made on very large scales (20000 tonnes par year) by the reaction of calcium(II) fluoirde, CaF2, with sulphuric acid.

CaF2(s) + H2SO4(l) (200°C) → 2HF(g) + CaSO4(s)

Solid state structure

  • Geometry of hydrogen: 1 coordinate: terminus
  • Prototypical structure:

Crystal structure of hydrogen fluoride

Isotope pattern

What follows is the calculated isotope pattern for the HF unit with the most intense ion set to 100%.

Formula: H1F1

mass  %
20 100.0 __________________________________________________
21 0.0

References

The data on these compounds pages are assembled and adapted from the primary literature and several other sources including the following.

  • R.T. Sanderson in Chemical Periodicity, Reinhold, New York, USA, 1960.
  • N.N. Greenwood and A. Earnshaw in Chemistry of the Elements, 2nd edition, Butterworth, UK, 1997.
  • F.A. Cotton, G. Wilkinson, C.A. Murillo, and M. Bochmann, in Advanced Inorganic Chemistry, John Wiley & Sons, 1999.
  • A.F. Trotman-Dickenson, (ed.) in Comprehensive Inorganic Chemistry, Pergamon, Oxford, UK, 1973.
  • R.W.G. Wyckoff, in Crystal Structures, volume 1, Interscience, John Wiley & Sons, 1963.
  • A.R.West in Basic solid state chemistry Chemistry, John Wiley & Sons, 1999.
  • A.F. Wells in Structural inorganic chemistry, 4th edition, Oxford, UK, 1975.
  • J.D.H. Donnay, (ed.) in Crystal data determinative tables, ACA monograph number 5, American Crystallographic Association, USA, 1963.
  • D.R. Lide, (ed.) in Chemical Rubber Company handbook of chemistry and physics, CRC Press, Boca Raton, Florida, USA, 77th edition, 1996.
  • J.W. Mellor in A comprehensive treatise on inorganic and theoretical chemistry, volumes 1-16, Longmans, London, UK, 1922-1937.
  • J.E. Macintyre (ed.) in Dictionary of inorganic compounds, volumes 1-3, Chapman & Hall, London, UK, 1992.

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hydrogen atomic number