Bismuth(III) iodide

Bismuth(III) iodide is the inorganic compound with the formula BiI3. This gray-black solid is the product of the reaction of bismuth and iodine, which once was of interest in qualitative inorganic analysis.[3][4]

Bismuth(III) iodide
IUPAC name
Bismuth(III) iodide
Other names
Bismuth iodide, bismuth triiodide
3D model (JSmol)
ECHA InfoCard 100.029.207
Molar mass 589.69 g/mol
Appearance Greenish-black crystals
Density 5.778 g/cm3
Melting point 408.6 °C (767.5 °F; 681.8 K)
Boiling point 542 °C (1,008 °F; 815 K)[1]
0.7761 mg/100 mL (20 °C)
Solubility 50 g/100 mL ethanol
50 g/100 mL 2 M hydrochloric acid
−200.5·10−6 cm3/mol
Trigonal, hR24
R-3, No. 148
Corrosive (C)
R-phrases (outdated) R34
S-phrases (outdated) S26, S27, S36/37/39, S45[2]
NFPA 704 (fire diamond)
Related compounds
Other anions
Bismuth(III) fluoride
Bismuth(III) chloride
Bismuth(III) bromide
Other cations
Nitrogen triiodide
Phosphorus triiodide
Antimony triiodide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Bismuth(III) iodide adopts a distinctive crystal structure, with iodide centres occupying a hexagonally closest-packed lattice, and bismuth centres occupying either none or two-thirds of the octahedral holes (alternating by layer), therefore it is said to occupy one third of the total octahedral holes.[5][6]


Bismuth(III) iodide forms upon heating an intimate mixture of iodine and bismuth powder:[7][8]

2Bi + 3I2 → 2BiI3

BiI3 can also be made by the reaction of bismuth oxide with aqueous hydroiodic acid:[9]

Bi2O3(s) + 6HI(aq) → 2BiI3(s) + 3H2O(l)


Since bismuth(III) iodide is insoluble in water, an aqueous solution can be tested for the presence of Bi3+ ions by adding a source of iodide such as potassium iodide. A black precipitate of bismuth(III) iodide indicates a positive test.[10]

Bismuth(III) iodide forms iodobismuth(III) anions when heated with halide donors:[11]

2 NaI + BiI3 → Na2[BiI5]


  1. Norman, Nicholas C. (1998), Chemistry of Arsenic, Antimony and Bismuth, Springer, p. 95, ISBN 0-7514-0389-X, retrieved 2008-06-03
  2. "341010 Bismuth(III) iodide 99%". Sigma-Aldrich. Retrieved 2008-06-19.
  3. "Bismuth iodide", McGraw-Hill Dictionary of Scientific and Technical Terms, McGraw-Hill, 2003, retrieved 2008-06-19
  4. Turner, Jr., Francis M.; Berolzheimer, Daniel D.; Cutter, William P.; Helfrich, John (1920), The Condensed Chemical Dictionary, New York: Chemical Catalog Company, p. 107, retrieved 2008-06-19
  5. Smart, Lesley; Moore, Elaine A. (2005), Solid State Chemistry: An Introduction, CRC Press, p. 40, ISBN 0-7487-7516-1, retrieved 2008-06-19
  6. Mackay, Rosemary Ann; Henderson, W. (2002), Introduction to Modern Inorganic Chemistry, CRC Press, pp. 122–6, ISBN 0-7487-6420-8, retrieved 2008-06-19
  7. Watt, George W.; Hakki, Wafai W.; Choppin, Gregory R. (1953). "Bismuth(III) Iodide (Bismuth Triiodide)". Inorganic Syntheses. 4: 114–116. doi:10.1002/9780470132357.ch38.
  8. Erdmann, Hugo; Dunlap, Frederick Leavy (1900), Handbook of Basic Tables for Chemical Analysis, New York: John Wiley & Sons, p. 76, retrieved 2008-06-19
  9. Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 559. ISBN 978-0-08-037941-8.
  10. Bruno, Thomas J.; Svoronos, Paris D. N. (2003), Handbook of Basic Tables for Chemical Analysis, CRC Press, p. 549, ISBN 0-8493-1573-5, retrieved 2008-06-19
  11. Norman, Nicholas C. (1998), Chemistry of Arsenic, Antimony and Bismuth, Springer, pp. 168–70, ISBN 0-7514-0389-X, retrieved 2008-06-19
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