The Reaction of Dinitrogen Pentoxide with Hydrogen Chloride

Abstract

The kinetics of the reaction N205 + HCI = N02CI + HN03 is similar to that of N205 + H20 = 2HN03, and both appear to have a slow homogeneous bimolecular path which is readily masked by a faster nitric acid catalyzed heterogeneous process. Near room temperature the homogeneous rate of the HCI reaction has a rate constant of 4.2 M-1 s-1 which can be compared to the corresponding value of 7.8 M"1 s-1 reported in the literature for the hydrolysis reaction. In polluted atmosphere containing HCI, the fate of N2O5 depends, therefore, on both H20 and HCI. The experimental rate equations suggest that nitric acid dimers, trimers, and hydrates on the walls of the reaction vessel may account for the heterogeneous reactions of N205 with HCI and H20.