Jan Kapała

Thermodynamic study of the CsCl–CeCl3 system by Knudsen effusion mass spectrometry

The vaporization of samples of different chemical and phase compositions covering the complete concentration range of the CsCl–CeCl3 system was investigated in the temperature range between 749 K and 1098 K by the use of Knudsen effusion mass spectrometry. The gaseous species CsCl, Cs2Cl2, CeCl3, Ce2Cl6 and CsCeCl4 were identified in the vapor and their partial pressures determined. The thermodynamic stability of CsCeCl4(g) was evaluated by second law treatment of the equilibrium partial pressures. The thermodynamic activities of CsCl and CeCl3 were obtained at 950 K in the two phase fields {liquid+Cs3CeCl6(s)} and {CsCe2Cl7(s)+CeCl3(s)} from the partial pressures of the vapor components. The Gibbs free energies of formation from the constituent halides of the pseudobinary phases Cs3CeCl6(s) and CsCe2Cl7(s) were evaluated from the thermodynamic activities of the components. The results are discussed with other literature data for the studied system.

Thermodynamics of sublimation of cadmium halides investigated by the mass-spectrometric method

Abstract The vapour pressures of cadmium chloride, bromide, and iodide were measured by the Knudsen-effusion mass spectrometry, and are expressed by the equations: ln {p( CdCl 2 )/ Pa } = −(20030+220)( K /T)+(29.22±0.34),(560 to 700 K ) , ln {p( CdBr 2 )/ Pa } = −(17110+410)( K /T)+(26.47±0.67),(560 to 670 K ) , ln {p( CdI 2 )/ Pa } = −(16770+200)( K /T)+(29.47±0.37),(460 to 590 K ) . The values of second- and third-law enthalpy and entropy of sublimation at 298.15 K have been calculated.

Mass spectrometric and theoretical study of the mixed complex NaNdCl4(g)

Abstract The vaporisation of the NaCl–NdCl3 system was investigated at 833–1116 K using Knudsen effusion mass spectrometry. The vapour species NaCl, NdCl3, and NaNdCl4 were found in the equilibrium vapour and their partial pressures were evaluated. Theoretical calculations of the NaNdCl4(g) structure were performed and the thermodynamic functions of the complex species were evaluated. The enthalpy change of the dissociation reaction NaNdCl4(g)=NaCl(g)+NdCl3(g) was computed by the second and third law methods. The value of ΔdH°(298)=256.5±7.0 resulted from this computation. The volatility enhancement of NdCl3 by the formation of the vapour complex NaNdCl4 was estimated from obtained thermodynamic data of gaseous and condensed phases.

Mass spectrometry of the {x TlCl + (1 — xTlBr} system: determination of solid-component activities and calculation of mass spectra of gas

Abstract The mass spectrum of the vapours over the { x TlCl + (1 — x )TlBr} system has been measured over the temperature range 540–600 K. Tl + , TlCl + , TlBr + , Tl 2 + , Tl 2 Cl + and Tl 2− , Br + ions were found as well as trace amounts of Tl 2 Cl 2 + , Tl 2 Br 2 + and Tl 2 ClBr + . By measuring the ion intensity ratios, the activities over the full composition range, the excess enthalpies, the excess entropies and the excess thermodynamic potentials were determined. The activities were used for resolving the mass spectrum of the dimers and for determining the pressure equilibrium constant for the formation reaction of a mixed dimer.

Vaporization of LnCl3 and thermochemistry of Ln2Cl6(g), Ln=Ce, Pr, Nd, Dy

Abstract The vaporization of LnCl 3 , Ln=Ce, Pr, Nd, Dy, was investigated by Knudsen effusion mass spectrometry. The monomer and dimer partial pressures in the equilibrium vapor of the compounds were determined. Molecular parameters of LnCl 3 (g) and Ln 2 Cl 6 (g) were determined theoretically and the thermodynamic functions of these species were computed applying statistical thermodynamics. The enthalpies of sublimation of LnCl 3 (g) were evaluated according to the second- and third-law methods. Recommended values of Δ sub H o (298)=334.8±7.2 kJ mol −1 (CeCl 3 ), 323.3±3.5 kJ mol −1 (PrCl 3 ), 317.3±6.4 kJ mol −1 (NdCl 3 ), and 305.3±6.3 kJ mol −1 (DyCl 3 ), resulted for the sublimation enthalpies of gaseous species given in brackets by compilation of the present study with the data available in the literature. The enthalpies of sublimation Δ sub H o (298)=443.2±12.0 kJ mol −1 (Ce 2 Cl 6 ), 418.7±12.1 kJ mol −1 (Pr 2 Cl 6 ), 414.8±11.3 kJ mol −1 (Nd 2 Cl 6 ), and 354.1±11.3 kJ mol −1 (Dy 2 Cl 6 ), were obtained for dimeric species by the use of the third law method.

The thermodynamic properties of the gaseous dimer of CdI2

The vaporization of CdI2(s) was investigated in the temperature range between 534 and 613 K by the Knudsen effusion mass spectrometry. The Cd2I4(g)-dimer content in the equilibrium vapor of CdI2(s) was determined for the first time. The enthalpies of sublimation and dissociation of Cd2I4(g) were evaluated according to the third-law method using the experimental p(CdI2)/p(Cd2I4) ratio. Molecular parameters and the thermodynamic functions of Cd2I4(g) were determined theoretically. Enthalpy of sublimation, 2 CdI2(s)=Cd2I4(g), was obtained as: ΔsubH0(298.15 K)=222.5±6.2 kJ mol−1, and enthalpy of dissociation, Cd2I4(g)=2 CdI2(g), was determined as ΔdH0(298.15 K)=70.7±7.0 kJ mol−1. The standard enthalpy of formation of Cd2I4(g) was obtained as ΔfH0(298.15 K)=−188.1±6.3 kJ mol−1.

Thermodynamics of the sublimation of thallium halides investigated by the mass-spectrometric method

Abstract The vapour pressures of monomeric and dimeric molecules of thallium chloride, bromide, and iodide are expressed by the equation: log 10 ( p Pa ) = −A( K T ) + B . The values of A and B are given. The values of second-law enthalpies of sublimation Δ s g H m o (298.15 K)/(kJ · mol −1 ) are: 140.8, 176.9, 136.0, 181.4, 133.1, and 174.8 for TlCl, Tl 2 Cl 2 , TlBr, Tl 2 Br 2 , TlI, and Tl 2 I 2 , respectively. The respective third-law enthalpies of sublimation Δ s g H m o (298.15 K)/(kJ · mol −1 ) are: 138.2, 172.7, 138.6, 177.1, 139.6, and 187.8.

Separation of mass spectra of binary salt systems: calculations of mass spectra of pure system components from binary data

Abstract The problem of the origin of fragment ions from the gaseous phase above salt systems has been considered. The methodof calculation of the mass spectra of pure system components and other gaseous species is presented. The calculations were performed for simulated data of a hypothetical { x MX 2 + (1 − x )MY 2 } system and two systems investigated experimentally: { x · dCl 2 + (1 − x )CdBr 2 }, and { x CdBr 2 + (1 − x )CdI 2 }.

Thermodynamics of {xCdBr2 + (1−x)CdI2}(s) investigated by mass spectrometry

The mass spectrum over {xCdBr2 + (1−x)CdI2}(s) measured at the temperature 550 K exhibits the ions Cd+, CdBr+, CdI+, CdBr2+, CdI2+, and CdBrI+. The excess molar Gibbs free energy of the solid mixture has been obtained: GEm(550 K)(J·mol−1) = x(1−x){(−306±114)+(−1404±172)(2x−1)} The mass spectrum of CdBrI(s) and the standard equilibrium constant of the reaction of formation of CdBrI(g) from 12CdBr2(g) and 12CdI2(g) at 550 K have been calculated.

Excess molar Gibbs free energy of {xTlBr+(1−x)TlI} investigated by mass spectrometry

Abstract The mass spectra of vapours over {(1− x )TlI+ x TlBr}(s) have been measured in the temperature range 540 to 580 K. Tl + , TlBr + , TlI + , Tl 2 Br + , Tl 2 I + , and Tl 2 + ions have been found. The excess molar Gibbs free energy at 560 K has been determined by measuring intensity ratios I (TlBr + )/ I (TlI + ): G m E / ( J ⋅ mo l − 1 ) = ( 1 − x ) x { 3750 + 1260 ( 2 x − 1 ) }