Mass-loss effusion

Summary of literature data Spinning rotor fraction gauge Torsion mass loss effusion Static method ... 

Da Silva and Monte [5] have measured the vapor pressure of crystalline benzoylacetone by the Knudsen mass-loss effusion method over the temperature range, 292-302°C. One set of their data is given in Table 8.5. As the vapor pressure is low, and the temperature range is small, use the... 

The reliable studies from which the Gibbs energy of formation of ThO(g) can be derived are listed in Table VII-2 further details are given in the relevant Appendix A entries. The most reliable of these are the studies which involve, in part, mass-loss effusion to calculate the absolute pressures of ThO(g) in the diphasic Th(l) + Th02(cr) phase field, whereas the remaining mass-spectrometric studies relied on estimated ion cross-sections. Table VII-2 includes the calculated enthalpy of formation of ThO(g) from each of the studies, based on a third-law analysis. The stndy by... 

DAR/MCC] Th(l) + Xh02(cr) 2ThO(g) Mass-loss effusion and mass-spectrometry 1984 - 2564 -28.6 23.5... 

ACK/RAU2] Mass-loss effusion Th(l) + Th02(cr) 2ThO(g) 2080 - 2214 -26.5 6.0... 

ACK/RAU2] Mass-loss effusion mass- — 2400 - 2800 No new No new... 

The vaponr pressure of the solid was determined by mass-loss effusion from a nickel cell, from 1055 to 1297 K. Corrosion tests showed neghgible reaction between Ni and TI1F4, even in the molten state. In one ran, the effusate was collected on a tanta-Inm cyhnder and was fonnd to be TI1F4, by chemical and X-ray analysis. 

Mass-loss effusion studies have been made of the vaporisation of compounds of thorium and uranium with silicon and germanium, and of other compounds of U with Pb, Sn, In, and Ga. Gibbs energies of formation are reported for the compounds ThSiz, ThsSis, ThSi, ThsSiz for the temperature range ca. 1685 < T < 1961 K and ThGes,... 

The X-ray examination showed a tetragonal structure and the material was presumably the tetragonal p-modification normally found in such preparations. Mass-loss effusion measurements were made from a platinum Knudsen cell from 671 to 982 K, with good reproducibility. It was observed that a sample of ThCU contaminated with water gave appreciably lower vapour pressures, between those for the anhydrous ThCLt and the decomposition pressure of ThOCl2 (see [1972KNA/MUL]). 

Among the most reliable methods for measuring the vapour pressures of solids as a function of temperature are the mass loss [86] or torsion [87] Knudsen effusion techniques. The torsion-effusion method is a complementary method to mass-loss effusion and both have often been measured simultaneously [88,89]. This combination provides additional information useful in assessing the presence of association in the vapour because vapour pressure information is provided that is dependent (mass loss) and independent (torsion) of the molar mass of the effusing vapour. 

As cited previously, one of the most successful methods for the indirect determination of enthalpies of sublimation is based on the Knudsen-cell mass-loss effusion methods. Recently equipment has been described with three [189] and nine [190] Knudsen cells used for simultaneous measurements. The torsion effusion method has been used recently to determine enthalpies of sublimation of uracil derivatives [191] and sublimation enthalpies have also been determined in drop calorimeters [192,193]. 

During the last decade, a number of sublimation enthalpies have been measured by transpiration or transference techniques [91,199-204]. The data obtained with this method are in agreement with those obtained by the Knudsen cell mass-loss effusion method, correlation gas chromatography [205] and thermogravimetry [206]. 

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