Chemical elements
    Physical Properties
    Chemical Properties
      Lead Tetramethyl
      Lead Tetraethyl
      Lead Tetraphenyl
      Lead Ethoxide
      Lead Fluoride
      Lead Tetrafluoride
      Hydrofluoplumbic Acid
      Lead Chloride
      Lead Chloride Double Salts
      Basic Lead Chlorides
      Lead Tetrachloride
      Ammonium Plumbichloride
      Lead Chlorite
      Lead Chlorate
      Lead Perchlorate
      Lead Dibromide
      Double Salts of Lead Bromide
      Basic Lead Bromides
      Lead Bromate
      Lead Iodide
      Lead Iodide Complex Salts
      Basic Lead Iodides
      Lead Tetra-iodide
      Lead Iodate
      Lead Periodates
      Lead Suboxide
      Lead Monoxide
      Lead Hydroxides
      Lead Dioxide
      Plumbic Acids
      Hexahydroxyplumbic Acid
      Colloidal Plumbic Acid
      Potassium Plumbate
      Lead Plumbate
      Calcium Orthoplumbate
      Lead Orthoplumbate
      Red Lead
      Metaplumbic Acid
      Calcium Metaplumbate
      Lead Metaplumbate
      Basic Lead Plumbate
      Lead Sulphide
      Lead Sulphohalides
      Lead Polysulphide
      Lead Sulphite
      Lead Sulphates
      Lead Sulphate
      Basic Lead Sulphates
      Lead Hydrogen Sulphate
      Plumbic Sulphate
      Lead Persulphate
      Lead Thiosulphate
      Lead Dithionate
      Lead Selenide
      Lead Selenite
      Lead Selenate
      Lead Telluride
      Lead Tellurite
      Lead Azide
      Lead Azoimide
      Lead Hydrazoate
      Lead Imide
      Lead Hyponitrite
      Lead Nitrites
      Lead Nitrate
      Lead saltpetre
      Basic Lead Nitrates
      Lead Hypophosphite
      Lead Phosphite
      Lead Orthophosphate
      Lead Monohydrogen Phosphate
      Lead Dihydrogen Phosphate
      Lead Pyrophosphate
      Lead Metaphosphate
      Lead Arsenite
      Lead Orthoarsenate
      Lead Hydrogen Arsenate
      Lead Pyroarsenate
      Lead Antimonate
      Lead Carbonate
      White Lead
      Lead Formate
      Lead Acetate
      Sugar of Lead
      Complex Lead Acetates
      Plumbic Acetate
      Lead Tetra-acetate
      Lead Oxalate
      Lead Tartrate
      Lead Silicates
      Lead Borates
      Normal Lead Chromate
      Lead Dichromate
      Basic Lead Chromate
      Lead Molybdate
      Lead Tungstate
      Lead Metatungstate
      Lead Diuranate
      Lead Peruranate
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Lead Iodide, PbI2

Lead Iodide, PbI2, may be obtained by dissolving lead in hydriodic acid, or by precipitating a lead salt by means of a soluble iodide. When obtained in the latter way it is a bright yellow precipitate, which dissolves in much hot water and separates again on cooling in golden yellow six-sided plates, The density of lead iodide is 6.16; when the dry salt is heated it becomes reddish yellow, then bright red and brownish black, and finally melts to a reddish brown liquid at about 380° C. Various estimations of the melting-point are as follow: Ramsay and Eumorfopoulus, 373° C.; Ehrhardt, 375° C.; Carnelley, between 374° C. and 387° C., with a mean value of 383° C. It boils between 861° C. and 954° C., and may be sublimed unchanged in an atmosphere of carbon dioxide.

The molecular heat of formation of lead iodide from its elements is 39,800 calories; or, according to Koref and Braune, 41,850 calories.

Dry lead iodide is stable in the air; but the moist salt, under the influence of sunlight, yields lead carbonate and dioxide together with free iodine. When the salt is heated in the air it loses iodine and forms an oxyiodide.

Solubility curves of lead halogens
Solubility curves of lead chloride, bromide, and iodide in water.
The solubility of lead iodide in water is as follows:

Temp. ° C015253545556580100
Grams PbI2 in 100 grams H2O0.04420.06130.07640.10420.14530.17550.21830.30230.436

According to von Ende, the solubility at 25° C. is 0.00158 gram-molecule per litre. This salt is thus much less soluble in water than the bromide or chloride. The solubilities of the three salts are shown in Fig.

The solubilities of lead chloride, bromide, and iodide at 20° C. have been determined by Bottger by comparing the electric conductivities of their saturated solutions with the conductivity of pure water. The following results were obtained: PbCl2 9.61×10-1, PbBr2 8.34×10-1, PbI2 0.47×10-1 grams per litre. Moreover, it was concluded that lead iodide is dissociated only into Pb•• and 2I' ions, no PbI•• ions being formed; the ion-concentration of this salt was 2.53×10-3 equivalents per litre, and the solubility product 8.10×10-9.

An aqueous solution of lead iodide is colourless the yellow colour being that of the solid salt, and not of Pb•• or I' ions. This salt is more soluble in alkali iodide and acetate solutions than in pure water, owing to the formation of complex ions. Indeed, lead iodide may be dissolved in concentrated potassium iodide solution and reprecipitated by dilution.

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