The Thermal Decomposition.of Sodium Carbonate by the Effusion Method

Motzfeldt, K.

doi:10.1021/j150524a011

Cited by 192 publications

(104 citation statements)

References 2 publications

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“…The measured pressure then depends on the ratio f = aC/A and on the conductance of the cell [59,60], (7) where α is the evaporation coefficient [61] of the effusing species, W Α the Clausing factor of the inner cell body, p m the measured pressure, and p eq the equilibrium pressure. This relation was confirmed by Monte-Carlo calculations [62].…”

confidence: 99%

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High-temperature mass spectrometry: Instrumental techniques, ionization cross-sections, pressure measurements, and thermodynamic data (IUPAC Technical Report)

Drowart

Chatillon

Hastie

et al. 2005

Pure and Applied Chemistry

234

184

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An assessment of high-temperature mass spectrometry and of sources of inaccuracy is made. Experimental, calculated, and estimated cross-sections for ionization of atoms and inorganic molecules typically present in high-temperature vapors are summarized. Experimental cross-sections determined for some 56 atoms are generally close to theoretically calculated values, especially when excitation–autoionization is taken into account. Absolute or relative cross-sections for formation of parent ions were measured for ca. 100 molecules. These include homonuclear diatomic and polyatomic molecules, oxides, chalcogenides, halides, and hydroxides. Additivity of atomic cross-sections supplemented by empirical corrections provides fair estimates of molecular cross-sections. Causes of uncertainty are differences in interatomic distances and in shapes of potential energy curves (surfaces) of neutral molecules and of molecular ions and tendency toward dissociative ionization in certain types of molecules. Various mass spectrometric procedures are described that render the accuracy of measured thermodynamic properties of materials largely independent of ionization cross-sections. This accuracy is comparable with that of other techniques applicable under the conditions of interest, but often only the mass spectrometric procedure is appropriate at high temperatures.

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confidence: 99%

“…Ionization cross-section measurements as a function of energy for different fragmentation channels were so determined for C 60 and C 70 [195,196]. • Comparison of intensities for species when the ratio of their pressures is fixed by congruency conditions [4,8].…”

Section: High-temperature Mass Spectrometric Determinations Of Ionizamentioning

confidence: 99%

High-temperature mass spectrometry: Instrumental techniques, ionization cross-sections, pressure measurements, and thermodynamic data (IUPAC Technical Report)

Drowart

Chatillon

Hastie

et al. 2005

Pure and Applied Chemistry

234

184

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“…This suggests that the following reaction (Eq. 13) is operative in the Na 2 SiO 3 /Na 2 CO 3 mixture: Na 2 CO 3 ϩ2Na 2 SiO 3 ϭNa 6 Si 2 O 7 ϩCO 2 (g)......... (13) Motzfeldt 9) suggested that the following reaction of Eq. (14) was responsible for the decomposition of pure Na 2 CO 3 , based on the observations that the Na 2 O content in Na 2 CO 3 (l) was in the order of 1 mass%, and Na 2 O was not detected in the remaining sample:…”

Section: Reaction Pathsmentioning

confidence: 99%

Decomposition of Na2CO3 by Interaction with SiO2 in Mold Flux of Steel Continuous Casting.

Kim

Lee

2001

ISIJ International

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The effect of SiO 2 addition on the decomposition of Na 2 CO 3 was investigated using the thermo-gravimetric and differential scanning calorimetric method (TG-DSC). Addition of SiO 2 greatly enhanced the decomposition of Na 2 CO 3 . The main decomposition reaction began to take place at a eutectic temperature of the Na 2 O-SiO 2 system (800°C). The initial decomposition product was identified as Na 2 SiO 3 , irrespective of the mixing ratio of Na 2 CO 3 to SiO 2 . The governing reaction of the decomposition was concluded to be Na 2 CO 3 ϩSiO 2 ϭNa 2 SiO 3 (s)ϩCO 2 (g). The decomposition rate was independent of the Na 2 CO 3 /SiO 2 mixing ratio until either one has completely been exhausted and hence was not available any more for the above reaction. If surplus Na 2 CO 3 exists after formation of Na 2 SiO 3 by reacting with all SiO 2 , the remaining Na 2 CO 3 decomposes partly by reacting with Na 2 SiO 3 to form Na 6 Si 2 O 7 and partly by thermal self-decomposition. A liquid layer that was formed at the carbonate/additive interface facilitated the decomposition of the carbonates. The melting behavior of a mold flux was greatly influenced by the lowest eutectic temperature that a mold flux system can exhibit. The apparent activation energy of the decomposition of Na 2 CO 3 in existence with SiO 2 was estimated to be 426 kJ · mol Ϫ1.

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“…While both Whitman 14) and Motzfeldt 15) arrived at the conclusion that in a Knudsen cell of typical dimensions (cylindrical shape wherein height equals diameter), if A 0 =A s < 100, the saturated vapor pressure of the sample is very close to that near the orifice: P eq % P K . Moreover some researches 3) indicated that in such geometric shapes of the Knudsen cell the experimental error is great enough to mask the difference between P eq and P K .…”

Section: Principle Of the Knudsen Effusion Methodsmentioning

confidence: 99%

Vapor Pressure Measurements for Metal Chloride Systems by the Knudsen Effusion Method

et al. 2005

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Thermodynamic knowledge of metal chlorides, such as vapor pressure and activity in salt/slag, are of remarkable industrial interest, particularly in fields related to the recovery/recycle/reuse of metal materials. In this study, a new apparatus for measuring the vapor pressure of metal chlorides from molten salt/slag was designed and tested with reference compounds. The results are in a good agreement with the available literature data. Using the developed apparatus, vapor pressure measurements for a KCl-NaCl-CaCl 2 system have been performed. Using the measured data the activities of components were obtained. Simultaneously, the activities of components were calculated using a thermodynamic code, Factsage 5.2 wherein the Modified Quasi-chemical Model was employed to obtain the necessary thermodynamic parameters. The both data agree reasonably well with each other. The results suggested that the KCl-NaCl system exhibits similar behavior with ideal solution; while in the KCl-CaCl 2 and NaCl-CaCl 2 systems there are possible interactions between CaCl 2 and KCl/NaCl. For the ternary system KCl-NaClCaCl 2 , in some concentration range (mole fraction of NaCl 0.25-0.50) NaCl behaves as in an ideal solution, suggesting a larger affinity between KCl and CaCl 2 than that between NaCl and CaCl 2 .

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The Thermal Decomposition.of Sodium Carbonate by the Effusion Method

Cited by 192 publications

References 2 publications

High-temperature mass spectrometry: Instrumental techniques, ionization cross-sections, pressure measurements, and thermodynamic data (IUPAC Technical Report)

High-temperature mass spectrometry: Instrumental techniques, ionization cross-sections, pressure measurements, and thermodynamic data (IUPAC Technical Report)

Decomposition of Na2CO3 by Interaction with SiO2 in Mold Flux of Steel Continuous Casting.

Vapor Pressure Measurements for Metal Chloride Systems by the Knudsen Effusion Method

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