The kinetics of the thermal, gaseous hydrogen-fluorine reaction have been investigated by a colorimetric technique. The reaction has been found to be inhibited by oxygen and the inhibited reaction was studied mainly at 132O, but also from 122 to 162'. The experiments have been performed at a total pressure of about 645 mm., with oxygen varying from about 85 to 500 mm. Nitrogen and helium have been used to maintain the total pressure at the desired value. Hydrogen and fluorine pressures have been in the general range of -20-80 mm. It has been found that the rate decreases with added oxygen but reaches a limiting value unaffected by further oxygen addition. The limiting rate obeys the expression -d(Fz)/dt = k(F2)(H2)"' fairly well, but the curves of the integrated forms are linear only for about the first 50% of reaction, dropping off thereafter. The Arrhenius plot for the rates from 132 to 162' is linear, yielding an activation energy of 16.7 kcal./mole. The results are discussed in terms of a chain reaction involving the propagation steps, H + F2 -t H F + F; F + 0 2 + M -t FOO + M; and FOO + H2 + H F + O2 + H. Evidence is presented for an activation energy of 5-7 kcal./mole for the reaction F + Hz -+ HF + H and for a heat of formation for the BOO species of +3.5 kcal./mole.
The reaction between fluorine and tetrafluorohydrazine has been investigated from 35 to 86°. Nitrogen trifluoride has been shown to be the only product. The kinetics have been measured by a colorimetric technique and have been shown to be homogeneous. It has been found that the kinetic data obey the expression -d(F2)/dí = &(F2)(N2F4)Vi and k = 1.0 X 11•0*0•2 exp(-20,400 ± 400/RT) M~l/l sec.-1. It is proposed that k = ^% where K is the equilibrium constant for the dissociation of tetrafluorohydrazine and fc2 is the rate constant for the reaction NF2 + F2 -*• NFs + F.
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