Determination of Carbon in Steel by the Direct Combustion Method.

1914 ◽  
Vol 6 (10) ◽  
pp. 843-845 ◽  
Author(s):  
Wm. Brady
Keyword(s):  
Combustion Method ◽  
Direct Combustion

Determination of the Heat of Formation of Octafluorotoluene and Calculation of D[C6F5—F] – D[C6F5—CF3]

1973 ◽  
Vol 51 (22) ◽  
pp. 3662-3664 ◽  
Author(s):  
Michael J. Krech ◽  
Stanley James W. Price ◽  
Wayne F. Yared
Keyword(s):  
Material Balance ◽  
Combustion Method ◽  
Heat Of Formation ◽  
Enthalpies Of Formation ◽  
Direct Combustion ◽  
Fold Excess

The heat of formation of octafluorotoluene has been determined using the direct combustion method previously developed for hexafluorobenzene. As in the hexafluorobenzene case the combustion of octafluorotoluene in oxygen yields CO2, CF4, and F2. With a ten-fold excess of oxygen the CO2 to CF4 ratio is 3.85 ± 0.06. A full material balance was obtained. The value of ΔHf2980(C6F5CF3,g) = −303.2 ± 1.8 kcal mol−1 may be combined with the enthalpies of formation of C6F6, CF3, and F to give D[C6F5—F] – D[C6F5—CF3] = 55.7 ± 4.0 kcal mol−1.

scholarly journals Determination of ΔHf2980(C12F10,g) from studies of the combustion of decafluorobiphenyl in oxygen and calculation of D(C6F5—C6F5)

1979 ◽  
Vol 57 (12) ◽  
pp. 1468-1470 ◽  
Author(s):  
Stanley James W. Price ◽  
Henry J. Sapiano
Keyword(s):  
Material Balance ◽  
Combustion Method ◽  
Heat Of Formation ◽  
Direct Combustion ◽  
Related Compounds ◽  
Fold Excess

The heat of formation of decafluorobiphenyl has been determined by the direct combustion method previously developed and used for hexafluorobenzene and related compounds. As in the hexafluorobenzene case the combustion of decafluorobiphenyl in oxygen yields CO2, CF4, and F2. With a ten-fold excess of oxygen the CO2 to CF4 ratio is 5.85 ± 0.08. A full material balance was obtained. The value of ΔHf2980(C12F10,g) = −1263.2 ± 5.1 kJ mol−1 may be combined with ΔHf2980(C6F5,g) = −387.4 ± 12.0 kJ mol−1 to give D(C6F5—C6F5) = 488.4 ± 24.5 kJ mol−1. Also with ΔHf2980(C6F6,g) = −945.6 ± 8.0 kJ mol−1 ΔH2980 for reaction [3][Formula: see text]is calculated to be −628.0 ± 16.8 kJ mol−1.

Determination of ΔHf2980(C6F5Br, g) from studies of the combustion of bromopentafluorobenzene in oxygen and calculation of D[C6F5 — Br]

1977 ◽  
Vol 55 (24) ◽  
pp. 4222-4226 ◽  
Author(s):  
Michael J. Krech ◽  
Stanley James W. Price ◽  
Henry J. Sapiano
Keyword(s):  
Material Balance ◽  
Combustion Method ◽  
Heat Of Formation ◽  
Molar Ratio ◽  
Direct Combustion ◽  
A Value ◽  
Fold Excess

The heat of formation of bromopentafluorobenzene has been determined through the use of the direct combustion method which has been applied to hexafluorobenzene, octafluorotoluene, and iodopentafluorobenzene. While a platinum lined bomb is normally used for these types of compounds a steel bomb had to be adopted in this work. The combustion of bromopentafluorobenzene in the steel bomb yields CO2, CF4, F2, Br2, and BrF3. With a ten-fold excess of oxygen, the average CO2 to CF4 molar ratio is 7.29 ± 0.07. A material balance was obtained for carbon, fluorine, and bromine. The value of ΔHf2980(C6F5Br, g) = −711.6 ± 16.7 kJ mol−1 (−170.1 ± 4.0 kcal mol−1) has been combined with ΔHf2980(C6F5, g) = −387.4 kJ mol−1 (−92.6 kcal mol−1) and ΔHf2980(Br, g) = 111.7 kJ mol−1 (26.7 kcal mol−1) to obtain a value for D[C6F5—Br] of 435.9 kJ mol−1 (104.2 kcal mol−1).

Determination of ΔH0f298(C6F10,g) and ΔH0f298(C6F12,g) from studies of the combustion of decafluorocyclohexene and dodecafluorocyclohexane in oxygen and calculation of the resonance energy of hexafluorobenzene

1979 ◽  
Vol 57 (6) ◽  
pp. 685-688 ◽  
Author(s):  
Stanley James W. Price ◽  
Henry J. Sapiano
Keyword(s):  
Material Balance ◽  
Resonance Energy ◽  
Combustion Method ◽  
Heats Of Formation ◽  
Reaction Products ◽  
Molar Ratios ◽  
Direct Combustion ◽  
Related Compounds ◽  
Fold Excess

The heats of formation of decafluorocyclohexene and dodecafluorocyclohexane have been determined by the direct combustion method previously developed and used for hexafluorobenzene and related compounds. The combustion of decafluorocyclohexene and dodecafluorocyclohexane formed the reaction products CO2, CF4, and F2. In both cases a portion of the compound remained unburned. The unburned material was collected and quantitatively determined gravimetrically. A material balance was obtained for carbon and fluorine on the basis of CO2, CF4, and F2 and the amount of unburned compound. With a ten-fold excess of oxygen, the average CO2-to-CF4 molar ratios for C6F10 and C6F12 are 2.03 ± 0.01 and 1.35 ± 0.01, respectively. The values obtained for the heats of formation are ΔH0f298(C6F10,g) = −1906.6 ± 7.2 kJ mol−1 and ΔH0f298(C6F12,g) = −2368.9 ± 7.6 kJ mol−1. ΔH0f298 for the reaction C6F10(g) + F2(g) → C6F12(g) was calculated to be −462.3 ± 14.8 kJ mol−1 and the 'resonance energy' of C6F6 is estimated at −36.4 kJ mol−1.

Determination of ΔHf2980(C6F5I,g) from Studies of the Combustion of Iodopentafluorobenzene in Oxygen and Calculation of D(C6F5—X) Bond Dissociation Energies

1974 ◽  
Vol 52 (15) ◽  
pp. 2673-2678 ◽  
Author(s):  
Michael J. Krech ◽  
Stanley James W. Price ◽  
Wayne F. Yared
Keyword(s):  
Material Balance ◽  
Combustion Method ◽  
Heat Of Formation ◽  
Molar Ratio ◽  
Bond Dissociation Energies ◽  
Bond Dissociation ◽  
Dissociation Energies ◽  
Direct Combustion ◽  
Tenfold Excess

The heat of formation of iodopentafluorobenzene has been determined using the direct combustion method previously developed and used for hexafluorobenzene and octafluorotoluene. The combustion with oxygen yields CO2, CF4, F2, I2, and IF5. With a tenfold excess of oxygen the average CO2 to CF4 molar ratio is 11.08 ± 0.028. A material balance was obtained for carbon and fluorine. An apparent shortfall of about 30% in iodine has been related to the formation of IO2(OH) during analysis. The value of ΔHf2980 (C6F5I,g) = −133.2 ± 3.0 kcal mol−1 has been combined with D(C6F5—I) and ΔHf2980(I, g) to obtain ΔHf2980(C6F5,g) = −92.6 kcal mol−1 Using this value and the appropriate values of ΔHf2980 (C6F5X,g) and ΔHf2980(X, g), values of D(C6F5—X) have been calculated for X = OH, H, F, Cl, I, CH3, and CF3.

Generic Combustion Method for Determination of Crude Protein in Feeds: Collaborative Study

1989 ◽  
Vol 72 (5) ◽  
pp. 770-774 ◽  
Author(s):  
Rose A Sweeney
Keyword(s):  
Crude Protein ◽  
Collaborative Study ◽  
Combustion Method ◽  
Performance Requirements ◽  
General Terms ◽  
Relative Standard ◽  
Kjeldahl Method ◽  
Standard Deviations ◽  
And Performance

Abstract Nine laboratories participated in a collaborative study on determination of crude protein in animal feeds to compare a generically described combustion method with the AOAC mercury catalyst Kjeldahl method (7.015). The combustion method was written in general terms of method principle, apparatus specifications, and performance requirements. The sample set comprised closely matched pairs of feed ingredients and mixed products ranging from 10 to 90% protein. Ten pairs ground to 0.5 mm were the focus of the study; 4 pairs were ground to 1.0 mm for comparison. Nicotinic acid and lysine monohydrochloride were included as standards. Collaborators were instructed to report their results for performance checks using materials supplied. Only one laboratory failed to meet the proposed limits. Seven laboratories used the LECO Model FP-228 analyzer and 2 used the LECO CHN 600 analyzer. For the 0.5 mm pairs, repeatability standard deviations (sr) ranged from 0.09 to 0.58 for the Kjeldahl method and from 0.14 to 0.33 for the combustion method, with a pooled sr value of 0.28 and relative standard deviation (RSDr) of 0.59%. Reproducibility standard deviations (SR) ranged from 0.23 to 0.86 (Kjeldahl) and from 0.30 to 0.61 (combustion), with a pooled sR value of 0.52 and RSDR of 1.10%. Grand means for the samples ground to 0.5 mm were 47.65% protein by the combustion method and 47.41% protein by the Kjeldahl method. For samples ground to 1.0 mm, corresponding values were 31.82 and 31.50% protein. The generic combustion method has been approved interim official first action.

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