Kinetics of the Thermal Decomposition of C(2)F(6) in the Presence of H(2) at 1300 degrees-1600 degrees K

The thermal decomposition of hexafluoroethane in the presence of hydrogen has been studied in a single-pulse shock tube in the temperature range 1300 degrees to 1600 degrees K. The reactants were highly diluted with argon, the composition ratios being Ar:H(2):C(2)F(6)similar or equal to 7500:17.4:1. The principal reaction products containing carbon were fluoroform and tetrafluoroethylene. A reaction scheme which accounts for these products is proposed and the first-order rate constant for the primary step C(2)F(6)-> 2CF(3) is deduced: k(i)=4.3X 10(17) exp(-94 400 +/- 4000)/RT sec(-1). Accepting an activation energy of about 1 kcal/mole for the recombination of Us radicals leads to D(CF(3)-CF(3))similar or equal to 93 +/- 4 kcal/mole.