The overall decomposition of dinitrogen pentoxide, N2O5, proceeds to oxygen and an equilibrium mixture of NO2 and its dimer N2O4 both in the gas phase and in inert solvents. The reaction is not catalyzed, is not affected by the surface of the container, and is unaffected by the presence of a large number of possible impurities. In the gas phase, first-order kinetics hold down to very low pressures. Pa the reaction appears to follow second-order kinetics. The possible mechanisms which might account for this behavior are as follows.
Several mechanisms are possible.
2 O 3 have all electron spins paired while molecular oxygen has two unpaired spins and a spin change is not probable. The falloff at very low pressures arises because, as the number of collisions drops with decreasing pressure, the rapid rate of the equilibrium corresponding to K1 can no longer be maintained. The reaction would now appear as second-order in N 2 O 5 . Some of the mechanisms by which ozone could be catalytically destroyed by NO, by hydroxyl radicals, and by chlorofluorocarbons are as follows. Ozone in the lower atmosphere can be produced in the course of oxidation of carbon monoxide to carbon dioxide by hydroxyl radicals.