High-Purity Iron(II) Iodide: Preparation, Vapor Pressure, and Vapor Composition, 792 to 1138 K

Article abstract of DOI:10.1021/j100257a051

The preparation of hogh-purity iron(II) iodide from metallic iron and elemental iodine is described.The product is shown to have extremely low levels of hydrogen- and oxygen-containing impurities and is primarily intended for use in discharge lamps.The results of a high-temperature mass spectrometric study of iron(II) iodide are outlined.The vapor pressure above iron(II) iodide has been measured in the range 792-1138 K by the quasistatic method.The partial pressures of I2, FeI2, and Fe2I4 were derived from the vapor pressure and the corresponding mole fractions.The molar enthalpies of sublimation and evaporation for the vaporization of iron(II) iodide to FeI2(g) and Fe2I4(g) are calculated by the second-law and third-law methods.The uncertainties associated with these quantities are discussed.From the second-law treatment: FeI2(s) = FeI2(g), ΔH_m^o(298.15 K) = 209 +/- 6 kJ/mol; 2FeI2(s) = Fe2I4(g), ΔH_mo(298.15 K) = 321 =+/- 12 kJ/mol; FeI2(l) + FeI2(g), ΔH_m^o(295.15 K) = 150 +/- 2 kJ/mol; 2FeI2(l) = Fe2I4(g),ΔH_m^o(298.15) = 201 +/-2 kJ/mol