Thermal Decomposition of N2O4 and NO2 by Shock Waves

A study of the reactions N2O4 + M⇄2NO2 + M and 2NO2 + M⇄2NO + O2 + M was carried out using the shock-wave method. For the first of these two reactions the rate equation was taken to be d[N2O4] / dt = −kD1[N2O4][M] + kR1[NO2]2[M] based on previous results. For argon as the inert gas M, with a reactant mole fraction less than 0.1, the rate constant was found to be kD1 = 2.2 × 1014exp(− 11 000 / RT) liter/mole·sec. Incorporated in these results was the new application of fully dispersed shock waves and these weak waves were found to produce more accurate results than the conventional use of partly dispersed shock waves. For the second reaction, the rate equation was taken to be d[NO2] / dt = −kD2[NO2]2 − kD3[NO2][M], and with argon as the inert gas the dissociation rate constants were found to be kD2 = 3.0 × 109exp(− 26 900 / RT) liter/mole·sec and kD3 = 3.6 × 1013exp(− 65 400 / RT) liter/mole·sec. An analytical description of the flow fields agreed well with the experimental values which were determined by a light absorption technique.