Chemical elements
    Physical Properties
    Chemical Properties
      Strontium Hydride
      Strontium Fluoride
      Strontium Chloride
      Strontium Perchloride
      Strontium Bromide
      Strontium Perbromide
      Strontium Iodide
      Strontium Periodides
      Mixed Halides
      Strontium Oxychloride
      Strontium Hypochlorite
      Strontium Chlorite
      Strontium Chlorate
      Strontium Perchlorate
      Strontium Oxybromide
      Strontium Bromate
      Strontium Oxyiodide
      Strontium Iodate
      Strontium Periodate
      Strontium Manganite
      Strontium Manganate
      Strontium Permanganate
      Strontium Suboxide
      Strontium Oxide
      Strontium Hydroxide
      Strontium Peroxide
      Strontium Diperoxyhydrate
      Strontium Hydride
      Strontium Hydrosulphide
      Strontium Polysulphides
      Strontium Oxysulphide
      Strontium Thiosulphate
      Strontium Hyposulphite
      Strontium Sulphite
      Strontium Dithionate
      Strontium Tetrathionate
      Strontium Sulphate
      Acid Strontium Sulphate
      Strontium Pyrosulphate
      Strontium Selenide
      Strontium Selenite
      Strontium Selenate
      Strontium Telluride
      Strontium Tellurite
      Strontium Tellurate
      Strontium Chromate
      Strontium Dichromate
      Strontium Trichromate
      Strontium Chlorochromate
      Strontium Molybdate
      Complex Strontium Molybdates
      Strontium Tungstate
      Strontium Uranate
      Strontium Nitride
      Strontium Azide
      Strontium Ammonium
      Strontium Hexammoniate
      Strontium Amide
      Strontium Imide
      Strontium Imidosulphonate
      Strontium Hyponitrite
      Strontium Nitrohydroxylaminate
      Strontium Nitrite
      Strontium Nitrate
      Strontium Phosphide
      Strontium Dihydrohypophosphite
      Strontium Hydrophosphite
      Strontium Dihydrophosphite
      Strontium Orthophosphates
      Strontium Pyrophosphate
      Strontium Metaphosphate
      Basic Strontium Phosphate
      Strontium Arsenide
      Strontium Orthoarsenites
      Strontium Pyroarsenite
      Strontium Metarsenite
      Strontium Orthoarsenates
      Strontium Pyroarsenate
      Strontium Thioarsenites
      Strontium Thio-oxyarsenates
      Strontium Thioantimonite
      Strontium Antimonate
      Strontium Orthovanadate
      Strontium Metavanadate
      Strontium Pervanadate
      Strontium Carbide
      Strontium Carbonyl
      Strontium Formate
      Strontium Acetate
      Strontium Oxalate
      Strontium Carbonate
      Strontium Trithiocarbonate
      Strontium Perthiocarbonate
      Strontium Cyanide
      Strontium Cyanamide
      Strontium Thiocyanate
      Strontium Silicide
      Strontium Silicate
      Strontium Fluosilicate
      Strontium Stannate
      Strontium Orthoplumbate
      Strontium Titanate
      Strontium Zirconate
      Strontium Boride
      Strontium Borates
      Strontium Aluminates
      Strontium Ferrate
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Strontium Iodide, SrI2

Strontium Iodide, SrI2, is formed when metallic strontium is heated in iodine vapour. It may be prepared by the action of hydriodic acid, or iodine, and a reducing agent, on strontium hydroxide, carbonate, or sulphide, evaporation, and fusion of the residue in a current of gaseous hydriodic acid.

The heat of formation from its elements is 147.5 Cal. It is a white deliquescent compound of density 4.549 at 25° C., and melting-point 507° C., or probably higher, since most of Carnelley's results are rather low. It readily loses iodine if melted in contact with air, and in moist air at ordinary temperatures it is decomposed, forming iodine and strontium hydroxide.

Strontium iodide is even more soluble in water than either the bromide or the chloride. The heat of solution is 20.5 Cal. Etard found the following values for the solubility:

Temperature, ° C-20-10-3711183852778197105120175
Grams SrI2 in 100 grams solution60.060.362.263.063.463.564.866.070.574.079.279.480.886.5

Measurements of the densities of strontium iodide solutions have been made, and also of refractive indices and freezing-points, and of electrical conductivities. Electrical conductivity determinations of solutions in methyl, ethyl, and propyl alcohol, and in mixtures of these with water, have been made at 0° C. and 25° C.

Hydrates of Strontium Iodide

From solutions at ordinary temperatures, hexagonal crystalline plates of the hexahydrate separate out. According to Tassilly, the salt obtained at 60° C. contains 7 molecules of water, and the heat of solution is -4.47 Cal. The heat of hydration is, therefore, 25.24 Cal.

Etard separated a duodecahydrate at low temperatures, and concluded that a dihydrate, which may be isomorphous with barium chloride dihydrate, BaCl2.2H2O, is probably the stable form above 90° C.

Addition Compounds of Strontium Iodide

Strontium iodide forms addition compounds containing 1, 2, 4, and 6 molecules of ammonia. The compound, Sr(NH3)6I2, has a dissociation pressure of 50 mm. at 62° C., and the heat of formation from strontium iodide and ammonia at the same temperature is 13.40 Cal. Huttig has found compounds with 1, 2, 6, and 8 molecules of ammonia which attain a dissociation pressure of 100 mm. At 204°, 134°, 74.5°, and 31° C. respectively, the heats of formation being 11.0, 12.6, 15.5, and 18.3 Cal.
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