Kinetics of the Heterogeneous Hydrolysis of Dinitrogen Pentoxide over the Temperature Range 214-263 K.
Final rept. 25 Sep 79-12 Oct 80,
ROCKWELL INTERNATIONAL THOUSAND OAKS CA SCIENCE CENTER
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The kinetics of the heterogeneous hydrolysis of dinitrogen pentoxide N2O5 on sulfuric acid-water surfaces was studied over the temperature range 214 to 263K for reactive surfaces containing 48 to 100 mole sulfuric acid H2SO4. The measurements were made in a flow reactor system in which the gaseous reactants and products were monitored by infrared spectroscopy. The results of the experimental study showed the surface reaction to be mechanistically first order with respect to gaseous N2O5, the reactive surface area and time. The surface reaction rate was observed to increase with the water content of the reactive surface over the range 0 to 52 mole H2OH2SO4 and to have a positive activation energy over the temperature range studied. A significant decrease in the reaction rate was observed with the state change of the reactive surface from liquid to solid. Over the range of conditions studied the hydrolysis reaction efficiency was observed to be between 10 to the minus 5th power and 10 to the minus 4th power reactions per collision with the temperature dependence of the collision efficiency being described by the expression gamma 2.94 x 10 to the minus 3rd power exp 883T reactionscollision with an estimated or - 50 experimental uncertainty for a 52 mole H2OH2SO4 frozen surface for between 221 and 263K. The magnitude of this rate coefficient indicates that the heterogeneous hydrolysis of N2O5 is significant in establishing the overall partitioning of NO sub x in the photochemical ozone-NO sub x stratospheric cycle.
- Atmospheric Physics
- Inorganic Chemistry