. The reaction over the well, CF 3 + C 3 F 7 --→ ←--2 C 2 F 5 , was also studied. In the high-pressure limit, the rate coefficients for this reaction vanish (k 5,∞ = 0), and the rate constants at pressures between 0.001 atm and 100 atm have been plotted in Figure . The reaction It is worth noting that the geometric mean rule (as described for alkyl combination reactions ) can be used to reasonably predict rate coefficients for larger radical combinations.