Chemical elements
  Aluminium
    Isotopes
    Energy
    Preparation
    Physical properties
    Chemical properties
      Aluminium subfluoride
      Aluminium trifluoride
      Aluminium trichloride
      Aluminium tribromide
      Aluminium iodide
      Aluminium chlorate
      Aluminium perchlorate
      Aluminium bromate
      Aluminium periodate
      Aluminium suboxide
      Alumina
      Aluminium sesqui-oxide
      Aluminium peroxide
      Aluminium hydroxides
      Aluminates
      Tricalcium aluminate
      Sodilim aluminate
      Aluminium sesqui-sulphide
      Aluminium selenide
      Aluminium telluride
      Aluminium sulphite
      Aluminium sulphate
      Alums
      Sodium alum
      Potassium alum
      Ammonium alum
      Hydroxylamine alum
      Silver alum
      Pseudo-alums
      Aluminium dithionate
      Aluminium selenite
      Aluminium selenate
      Aluminium chromate
      Aluminium molybdate
      Aluminium silicomolybdate
      Aluminium tungstate
      Aluminium silicotungstate
      Aluminium phosphotungstate
      Aluminium nitride
      Aluminium phosphide
      Aluminium arsenide
      Aluminium nitrate
      Aluminium Phosphates
      Basic aluminium arsenite
      Aluminium carbide
      Aluminium carbonate
      Aluminium thiocyanate
      Aluminium oxalate
      Aluminium alkyls
      Aluminium Hydrocarbon
      Aluminium acetylacetonate
      Aluminium silicide
      Aluminium silicates
      Leucite
      Nephelite
      Spodumene
      Topaz
      Beryl
      Tourmaline
      Axinite
      Sodalite
      Hauynite
      Kaolinite
      Aluminosilicic acids aluminosilicates
      Aluminium Borides
      Aluminium Boride
      Aluminium Boride
      Aluminium borocarbides
      Aluminium borate
      Aluminium sodium perborate
    Applications
    PDB 1a6e-1zca
    PDB 2b8w-3i62
    PDB 3kql-5ukd

Aluminium iodide, AlI3






Aluminium iodide, AlI3, may be prepared by heating aluminium with iodine in a sealed tube, by passing iodine vapour over heated aluminium, or by adding aluminium to iodine dissolved in carbon disulphide. It separates from carbon disulphide in colourless crystals of density 2.63, melts at 125°, and boils at 350°; its critical temperature is 955°. At 444° the vapour density is 27.0 (air = 1), the formula Al2I6 requiring 28.2 (Devilleand Troost). The vapour forms an exclusive mixture with air. The molecular formula is Al2I6 in molten iodine, and in carbon disulphide solution.

Aluminium iodide is very soluble in liquid ammonia, from which the compound AlI3.2ONH3 (?) may be crystallised at -33° C. At 8-13° C. the crystals lose ammonia and leave the compound AlI3.6NH3. The liquid ammonia solution reacts with potassium amide to form a soluble aluminium ammonobasic iodide, Al(NH2)3.AlI3, which crystallises with six molecules of ammonia at the ordinary temperature and about twenty at low temperatures. This compound reacts with more potassium amide to produce an insoluble ammonobasic iodide, Al(NH2)3.Al(NH2)2I.NH3, which loses two molecules of ammonia at 160° C.

Aluminium iodide is very soluble in water; an aqueous solution can be readily prepared from aluminium or its hydroxide and hydriodic acid. Like the chloride and bromide, it forms a hexahydrate, AlI3.6H2O; it also forms a hydrate, 2AlI3.15H2O.

The double salts AlI3.KI, AlI3.NaI and AlI3.HgI2.8H2O are known.


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