Open AccessThe heat of combustion of beryllium in fluorine
Author(s) -
K.L. Churney,
George T. Armstrong
Publication year - 1969
Publication title -
journal of research of the national bureau of standards. section a. physics and chemistry
Language(s) - English
Resource type - Journals
eISSN - 2376-5704
pISSN - 0022-4332
DOI - 10.6028/jres.073a.024
Subject(s) - polytetrafluoroethylene , materials science , fluorine , combustion , beryllium , amorphous solid , polymer , analytical chemistry (journal) , polymer chemistry , chemistry , composite material , organic chemistry , metallurgy
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 H25 ° 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.