Simone Smoes

Mass spectrometric determination of the dissociation energies of the molecules GeS, ScS, YS, LaS and CeS

The dissociation energies of the gaseous monosulphides GeS, ScS, YS, LaS and CeS were determined : D°0(GeS)= 130.9±0.6; D°0(ScS)= 113.4±2.5; D°0(YS)= 125.7±2.5; D°0(LaS)= 137.5±2.5; and D°0(CeS)= 136.0±3.0 kcal/mole. In an appendix, selected values for the dissociation energies of the monoxides ScO, LaO, YO, CeO and VO are given: D°0(ScO)= 160.4±2.0; D°0(YO)= 170.4±2.5; D°0(LaO)= 190.3±2.5; D°0(CeO)= 188.6±3.5 and D°0(VO)= 148.8±2.5 kcal/mole.

Mass spectrometric determination of the dissociation energies of the gaseous rare earth monosulphides

The dissociation energies of the gaseous monosulphides NdS, EuS, GdS, HoS, and LuS were determined: D°0(NdS)= 112.2 ± 3.5; D°0(EuS)= 85.9 ± 3.5; D°0(GdS)= 124.5 ± 3.5; D°0(HoS)= 101.4 ± 3.5; D°0(LuS)= 120.2 ± 3.5 kcal mole–1. These dissociation energies, together with the previously measured values for LaS, CeS and PrS were compared with the dissociation energies of the corresponding oxides. The dissociation energies of the remaining rare earth sulphides were estimated on the basis of this comparison: D°0(SmS)= 92.6 ± 5.0; D°0(TbS)= 122.4 ± 5.0; D°0(DyS)= 98.1 ± 5.0; D°0(ErS)= 99.2 ± 5.0; D°0(TmS)= 86.9 ± 5.0; D°0(YbS)⩽38.8 kcal mole–1.

Determination of the atomization energies of CP, C2P, CP2 and C2P2 by high temperature knudsen cell mass spectrometry

Abstract The atomization energies of the molecule CP, previously identified and of C2P, CP2 and C2P2. characterized here, were determined: D0o(CP) = 509.6 ± 8 or 121.8 ± 2; ΔH0o, at (C2P) = 1124 ± 15 or 268.7 ± 3.5; ΔH0o, at (CP2) = 980 ± 15 or 234.3 ± 3.5 and ΔH0o, at (C2P2) = 1642 ± 15 or 392.5 ± 3.5 kJ mole−1 or kcal mole−1, respectively. The comparison of the measured atomization energies with the bond strengths suggests that C2P has the structure CCP, but that CP2 may be a mixture of both the isomers PCP and CPP.

Mass spectrometric determination of the dissociation energies of the gaseous rare earth monoselenides and monotellurides

The dissociation energies of the following gaseous monoselenides and tellurides were determined: [graphic ommitted] The dissociation energies of the remaining rare earth chalcogenides, Yb excepted, were estimated by comparison with the oxides and sulphides. They are: [graphic ommitted].

Mass spectrometric determination of heat of sublimation of uranium

The vapour pressure of uranium was determined between 1720 and 2340°K: –log Pu(atm)=(26,210 ± 270)/T–(5.920 ± 0.135). The heat of sublimation calculated therefrom is ΔH°s, 0(U)= 129.0 ± 2.0 kcal/g atom. This result is in agreement with independent measurements of the vapour pressure of uranium as well as with the values derived from thermochemical cycles based on the dissociation energies of the monoxide and dioxide of uranium and on the vaporization of the monocarbide, the dicarbide and the monosulphide of uranium.

The heat of sublimation of uranium and the consistency of the thermodynamic data for uranium compounds

Abstract A review of the thermochemical data for the vaporization of the oxides and carbides of uranium was made to derive indirect values for the heat of sublimation of uranium from the corresponding thermodynamic cycles. The values obtained are in good agreement with the direct value determined mass-spectrometrically by the authors, ΔH 0 298,8 ( U ) = 125,5 ± 2.5 kcal / g . atom and with the value ΔH 0 298,8 ( U ) = 126 ± 5 kcal / g . atom also determined mass spectrometrically by De Maria, Burns, Drowart and Inghram (J. Chem. Phys. 32 [1960] 1373).

Mass spectrometric determination of the dissociation energy of the molecule BO

The dissociation energy of BO was determined from a study of the reactions B(g)+ LaO(g)= BO(g)+ La(g), B(g)+ UO(g)= BO(g)+ U(g), B(g)+ UO2(g)= BO(g)+ UO(g). The value obtained is D°o(BO)= 191.2±2.3 kcal/mole.

Atomization energies of phosphorus oxides

The study by the mass-spectrometric Knudsen-cell method of the vapours in equilibrium with metal oxide + metal phosphide systems at 1000–1700 K made possible the identification of the molecules P2O3, P2O4, P2O5 and P3O6. Their atomization energies were determined, as well as those of the phosphorus oxides prevalent at low temperatures. These are : P2O3 : 2055±15, P2O4 : 2530±18, P2O5 : 3020±22, P3O6 : 4012±24, P4O6 : 4385 (+40, –60), P4O7 : 4956±23, P4O8 : 5516±25, P4O9 : 6066±27 kJ mol–1.

Notizen: The Dissociation Energies of Rhodium Phosphide and Platinum Phosphide

The identification of the neutral species effusing from the Knudsen cell was based, after their ionization by electron impact, on the measurement of the mass, the isotopic ratio, the intensity profile in the molecular beam and, where possible, the appearance potentials. In addition to the species already observed in the C P G d 7 , the R h C 3 , and the P t C 3 systems, the molecule RhP was observed. At 2500 K, for ionizing electrons of 20 eV, the relative intensities of P+ (corrected for a 7% contribution due to fragmentation of P2) , P2+, Rh+, RhP+ were about 5 • 104/l05/7 • 102/1 in the system C —P —Gd —Rh. In the case of Pt, at 2267 K the corresponding intensities were 8-103 /3-104 /6/1. Due to more pronounced interaction of Pt than of Rh with the C —P —Gd system, an appreciable vaporization of phosphorus occured at 2000 — 2200 K, thereby explaining the less favorable detection limit for the PtP molecule. The dissociation energies were determined using the reaction