Barium diiodide dihydrate

  • Formula: BaI2.2H2O
  • Hill system formula: Ba1H4I2O2
  • CAS registry number: [7787-33-9]
  • Formula weight: 427.166
  • Class: iodide
  • Colour: white
  • Appearance: crystalline solid
  • Melting point: 740°C; 539°C (dehydrates to form BaI2)
  • Boiling point:
  • Density: 5000 kg m-3

The following are some synonyms of barium diiodide dihydrate:

  • barium diiodide dihydrate
  • barium(II) iodide 2-water
  • barium diiodide 2-water

The oxidation number of barium in barium diiodide dihydrate is 2.


Barium iodide dihydrate is made by the neutralization of barium carbonate with HI in water. The product crystallizes as the hydrate BaI2.2H2O. If this heated, dehydration to anhydrous BaI2 occurs.

BaCO3 + 2HI(aq) → BaI2(aq)

Element analysis

The table shows element percentages for BaI2.2H2O (barium diiodide dihydrate).

Element %
Ba 32.15
H 0.94
I 59.42
O 7.49

Isotope pattern for BaI2.2H2O

The chart below shows the calculated isotope pattern for the formula BaI2.2H2O with the most intense ion set to 100%.


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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