Composition and thermochemistry of the equilibrium vapour of the systems NaI—FeI₂ and NaI—PbI₂

Abstract

The vaporization of NaI/FeI2 and NaI/PbI2 samples of equimolar composition was investigated in the temperature ranges between 574 to 683 K and 562 to 669 K, respectively, by using the mass spectrometric Knudsen effusion method. The gaseous species I. I2, Nal. (NaI)2 FeI2, (FeI2)2, FeI3, NaFel3, and Na2FeI4 (NaI—FeI2 system) as well as Nal, (Nal)2, PbI2, (PbI2)2, and NaPbI3 (NaI—PbI2 system) are present in the equilibrium vapours. The equilibrium partial pressures of these species were determined with the exception of I, I2, and Fel3. Enthalpies and entropies of dissociation resulted for the reactions as ΔdH2980 (Eq. (1)) = 184 ± 5 kJ mol−1, ΔdH2980 (Eq. (1)) = 043 ± 8 j mol−1K−1;ΔdH2980 (Eq. (2)) = 333 ± 9 kj mol−1, ΔdH2980 (Eq. (2)) = 274 ± 14 J mol−1 K−1; and ΔdH2980 (Eq. (3)) = 168 ± 5 J mol−1, ΔdH2980 (Eq. (3)) = 151 ± 9 j mol−1 K−1. Equilibrium constants for these reactions are additionally given. The pressures of NaFel3(g) and NaPb13(g) as well as their enthalpies of dissociation are discussed with respect to their significance for semi empirical rules.

Vaporization of DyBr3(s) and thermochemistry of the dimer homocomplex (DyBr3)2(g)

“…The probable overall errors of ⌬ r H 298 0 , ⌬ r S 298 0 and p in Tables II and III, due to statistical errors and estimated uncertainties, were calculated as described by Hilpert et al 19 The following probable uncertainties were assumed for the computation of overall errors: Ϯ5 K for the absolute error of the temperature measurement, Ϯ3 K at the lowest and ϯ3 K at the highest measurement temperature for the differential error, Ϯ18% for the pressure calibration constant, Ϯ10% for H Tm 0 ϪH 298 0 and S Tm 0 ϪS 298 0 , as well as Ϯ30% for the quotient of the ionization cross section used in the computation of the dimer partial pressure ͑Table III͒. Additionally, the uncertainties ͑in k Ϫ1 J mol Ϫ1 ͒ of Ϯ5, Ϯ10, and Ϯ12.6 were estimated for the ͓͑G T 0 ϪH 298 0 )/T] function of DyBr 3 ͑s͒, DyBr 3 ͑g͒, and ͑DyBr 3 ͒ 2 ͑g͒, respectively.…”

Formation thermodynamics of the rare earth vapour complexes: DyAl3Cl12and DyAl2Cl9

“…(33,34) The statistical errors calculated from the experimental data are within 20.2 kJ·mol −1 for D r G°m(DyAl 3 Cl 12 , g), 20.7 kJ·mol −1 for D r H°m(DyAl 3 Cl 12 , g), and 21.0 J·K −1 ·mol −1 for D r S°m(DyAl 3 Cl 12 , g) within the temperature range T = (654 to 777) K, but may be doubled for D r G°m(DyAl 2 Cl 9 , g), D r H°m(DyAl 2 Cl 9 , g), and D r S°m(DyAl 2 Cl 9 , g) within the temperature range T = (803 to 847) K. The estimated probable uncertainties may result by assuming the absolute errors of the chemical analysis for Dy 3+ and Cl − as 20.5 per cent, of the volume measurement of the ampoules 20.5 per cent, and of the temperature measurement as 22.0 K.…”

Study of the Vapor of the NaI ‐ ScI3 System: Vapor Composition, Thermochemistry of the Gaseous Heterocomplexes and , and Their Potential for Chemical Vapor Transport

“…Ref. (14)]. The value ~H = 47 -+ 9 kJ mo1-1 is derived from the experimental enthalpy of dissociation of NaScI4(g) (Table II) and of the homocomplexes (NaI)~ ( 5) and (Sci3)2 ( 6).…”

“…The one-compartment Knudsen cell was the same as reported in Ref. (14). The effusion orifice had a diameter of 0.3 mm and a length of 2 mm.…”

“…A ~ The probable overall errors of A~H%98, ~S 2~8, and Kp in Table II, due to statistical errors and estimated uncertainties, were calculated as described by Hllpert etal. (14). The following probable uncertainties were assumed for the computation of the overall errors: -+3 K for the absolute error of the temperature measurement, +-2 K at the lowest and T-2 K at the highest measurement temperature for the differential error, +-15% for the pressure calibration constant, +-30% for H~ -H%98 and S~ -S%98, and +-40% for the quotient of the ionization cross sections used in the computation of Kp.…”