The Heat of Combustion of Beryllium in Fluorine.

Autor: Churney KL; Institute for Materials Research, National Bureau of Standards, Washington, D.C. 20234., Armstrong GT; Institute for Materials Research, National Bureau of Standards, Washington, D.C. 20234.
Jazyk: angličtina
Zdroj: Journal of research of the National Bureau of Standards. Section A, Physics and chemistry [J Res Natl Bur Stand A Phys Chem] 1969 May-Jun; Vol. 73A (3), pp. 281-297.
DOI: 10.6028/jres.073A.024
Abstrakt: An experimental determination of the energies of combustion in fluorine of polytetrafluoroethylene film and powder and of mixtures of beryllium with polytetrafluoroethylene gives for reaction (1) Δ H 25 C ° = - 1022.22 kJ mol -1 (-244.32 kcal mol -1 ) with an overall precision of 0.96 kJ mol -1 (0.23 kcal mol -1 ) at the 95 percent confidence limits. The total uncertainty is estimated not to exceed ±3.2 kJ mol -1 (±0.8 kcal mol -1 ). The measurements on polytetrarluoroethylene give for reaction (2a) and reaction (2b) Δ H 25 ° C ° = - 10369.7 and -10392.4 Jg -1 , respectively. Overall precisions expressed at the 95 percent confidence limits are 3.3 and 6.0 Jg -1 , respectively. (1) Be ( c ) + F 2 ( g ) = BeF 2 (  amorphous  ) (2a) C 2 F 4 ( polymer powder ) + 2 F 2 ( g ) = 2 CF 4 ( g ) (2b) C 2 F 4 ( polymer film ) + 2 F 2 ( g ) = 2 CF 4 ( g ) Be 2 C and Be metal were observed in a small carbonaceous residue from the combustion of the beryllium-polytetrafluoroethylene mixtures. Methods of analysis for these substances were developed. Gases resulting from the solution of the solid residues in aqueous KOH were analyzed for H 2 and CH 4 by differential absorption in molecular sieves at low temperatures.
Databáze: MEDLINE
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