The vaporization behavior of the systems boron—carbon and boron—carbon—silicon has been studied with a mass spectrometer. In addition to the gaseous species characteristic of graphite, silicon carbide and boron, the molecules BC2, B2C, BCSi, BSi2, BC, and BSi were identified and their atomization energies measured. The values are: 294, 254, 247, 174, 106, and 68 kcal/mole, respectively. The atomization energies of SiC, Si2C, and SiC2 have been redetermined.
The infrared absorption spectra in the range 4000 to 400 cm-1 of the vapors above liquid H2SO4,1:1 H2-SO4-D2SO4, and D2S04 have been measured and assigned to the respective gaseous molecules as well as equilibrium concentrations of S03. S02 was observed as a decomposition product. Assignment of the frequencies to the normal modes was made using correlations with the related near-tetrahedral molecules X-S02-Y and with spectra of the condensed phases. Some frequencies are predicted for H2Cr04 and for unassociated gaseous chlorosulfonic acid.
The vapors issuing from mullite and graphite Knudsen cells containing pure metals and alloys of the triad Cu–Ag–Au have been analyzed mass spectrometrically. From the experimental ratios of diatomic to monoatomic species and the vapor pressures of the elements, the following dissociation energies are obtained: D00(Cu2)=45.5±2.2 kcalD00(AgAu)=47.6±2.2 kcalD00(Ag2)=37.6±2.2 kcalD00(AgCu)=40.7±2.2 kcalD00(Au2)=51.5±2.2 kcalD00(AuCu)=54.5±2.2 kcalThese are based on ΔH298vap=81.1, 68.4, and 87.5 kcal/g-atom for Cu, Ag, and Au where D00 of AgCu depends on the value for Cu, and D00 of AgAu and AuCu on Au. The uncertainties quoted do not include the uncertainty in ΔHvap.
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