Investigation of the gas phase reaction of dinitrogen pentoxide with water vapor

The gas phase reaction of N 2 O 5 with water vapor was investigated in a 17.3‐m 3 Teflon lined chamber. Temporal concentration profiles for ozone, total nitrogen oxides, and nitrogen dioxide were measured. Concentration profiles for N 2 O 5 and HNO 3 were calculated from a combination of measurements of nitrogenous species. A kinetic mechanism with an adjustable value for the rate constant of N 2 O 5 + H 2 O was used to model the experiments. From this analysis an upper limit value of k ⩽ 4 × 10 −7 ppm −1 min −1 for the gas phase reaction N 2 O 5 + H 2 O → 2HNO 3 was derived.