The heat of formation of boron trifluoride by direct combination of the elements

Abstract

The standard heat of formation of aluminum fluoride was calculated from the heats of combustion of Teflon and of aluminum-Teflon mixtures in fluorine. The heat measurements were made in a bomb calorimeter. [Equations not included.] For reaction (1), ?H?298 was found equal to - 10,350.7 ? 0.4 Jg-1 (-247.43 ? 0.01 kcal monomole-1), and for reaction (2) ?H?298 = ?H?f298 was calculated to be -1507.8 ? 1.2 kJ mole-1 (-360.37 ? 0.29 kcal mole-1). The latter uncertainties are the computed standard deviations of the means. The calculated standard heat of formation of aluminum fluoride is estimated to be accurate to within ? 6.6 kJ mole-1 (1.6 kcal mole-1). The measurements on Teflon were combined with existing data and the heat of formation of carbon tetrafluoride was calculated to be -221.8 kcal mole-1.