Formation energies of molecules and anions of europium bromides

Abstract

The content of saturated vapors above europium dibromide and Eu-EuBr 2 , Eu-Ba-BaBr 2 , EuBr 2 -LaBr 3 systems is investigated by means of high temperature mass spectrometry in the electron ion ization and thermoionic emission regimes. On the basis of the measured equilibrium constants for reactions with participation of molecules and negative ions, the enthalpies of formation Δ f (kJ/mol) are deter mined using the method of the third law of thermodynamics: -59 ± 13 (EuBr), -349 ± 19 (EuBr 2 ), and -861 ± 24 (Eu ).

Atomization Energies of LnX Molecules (Ln = Sm, Eu, and Yb; X = Cl, Br, and I)

“…The value Δ at H 298 ° = 346 ± 11 kJ mol –1 (Δ at H 0 ° = 343 ± 11 kJ mol –1 ) reported by us earlier for EuBr does not contradict that of this work, Δ at H 0 ° = 356 ± 13 kJ mol –1 . Nevertheless, it should be noted that both values are based on the same experimental data and their difference is solely due to different functions for the EuBr molecule used in ref and in this work. In both cases the comparative method was applied but based on different data.…”

“…In both cases the comparative method was applied but based on different data. In ref the functions of EuCl, EuCl 2 , and EuBr 2 were used as a comparison, whereas in this work those of LnX (Ln = Eu and Yb; X = F and Cl) and YbBr were employed. In our opinion, the latter approach is more reliable since it considers simple diatomic molecules only, whereas the uncertainties reported in ref were apparently underestimated.…”

“…In ref the functions of EuCl, EuCl 2 , and EuBr 2 were used as a comparison, whereas in this work those of LnX (Ln = Eu and Yb; X = F and Cl) and YbBr were employed. In our opinion, the latter approach is more reliable since it considers simple diatomic molecules only, whereas the uncertainties reported in ref were apparently underestimated. It should be also noted that the value of formation enthalpy for YbBr found earlier by another method and corresponding to Δ at H 0 ° = 261 ± 3 kJ·mol –1 is acknowledged to be erroneous.…”

Determination of the Work Function for Europium Dibromide by Knudsen Effusion Mass Spectrometry

“…The values Δ diss H °(EuBr 3 – ) and D at (EuBr 2 ) were calculated by Hess's law using the formation enthalpies of the reaction participants. The formation enthalpies Δ f H o (EuBr 2 , 298.15 K) = −349 ± 19 kJ·mol –1 and Δ f H °(EuBr 3 – , 298.15 K) = −861 ± 24 kJ·mol –1 were obtained and are discussed in ref . Additionally, the following reference data for Δ f H °(298.15 K) in kJ·mol –1 were used: 178.2 ± 3.0 for Eu, 111.86 ± 0.12 for Br, and −219.04 ± 0.23 for Br – .…”

“…Additionally, the following reference data for Δ f H °(298.15 K) in kJ·mol –1 were used: 178.2 ± 3.0 for Eu, 111.86 ± 0.12 for Br, and −219.04 ± 0.23 for Br – . The data were reduced to a temperature of 1264 K using the enthalpy increments of the reaction participants. ,, …”