Rate constants for the collisional dissociation of N2O5 by N2

Abstract

The rate constants for the collisional dissociation of N₂O₅ by N₂ are measured over the pressure and temperature ranges of 10 to 800 Torr and 285 to 384 K, respectively. The measurements are carried out in flow‐through reaction cells of different volumes, the N₂O₅ being detected by selected ion–molecule reactions in a flowing afterglow apparatus. The present rate constants are somewhat smaller than those of earlier studies and also suggest that the transition from second‐ to first‐order kinetics occurs at lower pressures than was earlier thought. The data are fitted to theoretical models of varying sophistication. The recommended values for use in extrapolation for the limiting low‐pressure and high‐pressure rate constants corresponding to the first‐order Troe extension of the Lindeman–Hinshelwood model for F^sc_cent = 0.572 are k₀ = 1.15×10⁻⁵ exp (−19.70 kcal/mol/RT) cm³ s⁻¹ and k₀₀ = 1.21×10¹⁷exp(−25.41 kcal/mol/RT) s⁻¹. Other forms yield similar results.