Margaret A. Frisch

Thermodynamic properties of CF and CF2 from molecular flow effusion and mass spectrometer investigations

The reaction of CF4 and C has been studied in the temperature range 1800–2500 K. Equilibrium data were obtained for species obtained in this temperature range by two techniques: (i) molecular flow effusion and (ii) effusion-mass spectrometry. Heats of formation were calculated from the reaction thermodynamics for the species CF(g), ΔH°f298 K= 58 ± 1 kcal/mol, and CF2(g), ΔH°f298 K=–41.7 ± 0.4 kcal/mol (third law). The S°298 of CF2(g) is 58.9 ± 1.2 cal/deg. mol (second law). Calculations provided thermodynamic limits for the species CF3(g) and C2F2(g).

GLASS COMBUSTION BOMB

A glass combustion bomb is described which has proved invaluable in working out suitable combustion conditions for inorganic materials. It is possible to observe relative combustion temperatures, rates of burning, melting of sample or combustion products, spattering, fuse wire temperature, etc., and to study the effects of these at different pressures and sample arrangements. It is imperative that suitable shielding be in place before the bomb is used. (B.O.G.)

Mass spectrometer studies of Al + H2O reactions in effusion cells and in atmospheric H2+ O2 flames

A two-fold mass spectrometer study of the Al + H2O reactions in effusion cells and in atmospheric H2+ O2 flames was conducted. The flame studies yielded a D°0 of 119.5±5 kcal/mole for AlO, in agreement with the results of previous thermochemical and spectroscopic investigations. A discussion concerning the discrepancy between the data obtained in these and previous flame experiments is presented. The major Al–O–H species in both the effusion and the flame studies was AlOH, with a ΔHf298 of –42.7±2 kcal/mole. The flame studies also produced other suboxides of aluminum, as well as the species AlO2H, for which a ΔHf298 of –90±5 kcal/mole was obtained.