Kinetics of Pb Reactions with N2O, Cl2, HCl, and O2 at High Temperatures

The title reactions of ground-state lead atoms have been studied in isolation in an HTFFR (high-temperature fast-flow reactor) at pressures in the 10−150 mbar range. Pb consumption rate coefficients were determined using atomic resonance absorption spectrometry at 217.0 and 283.3 nm. The following results, in cm3 molecule-1 s-1, have been obtained: Pb + N2O, k(650−1205 K) = 1.8 × 10-10 exp(−8948 K/T); Pb + Cl2, k(530−1165 K) = 2.3 × 10-10 exp(−718 K/T); Pb + HCl, k(1090−1320 K) = 8.2 × 10-10 exp(−17233 K/T). The precision limits vary somewhat between these measurements; the estimated 2σ accuracy limits are all about ±25%. The Pb + HCl result suggests that D0(Pb−Cl) = 318 ± 31 kJ mol-1. In contrast to the above homogeneous processes, the observations on the O2 reaction indicate the dominance of heterogeneous reactions. It is speculated that these lead primarily to PbO2 below 1000 K and to PbO above 1000 K.