Rate Constants for Reactions between Atmospheric Reservoir Species. 2. H2O

Article abstract of DOI:10.1021/j100352a027

The kinetics of the reactions of H2O with ClONO2, N2O5, O3, and COCl2 have been investigated by using a large-volume static cell and a Fourier transform infrared spectrometer at 296 K.Upper limits for the homogenous gas-phase reaction rate constants of the ClONO2 + H2O, N2O5 + H2O, O3 + H2O, and COCl2 + H2O reactions were found to be 3.4 x 10^-21, 2.8 x 10^-21, 1.1 x 10^-22, and 1.2 x 10^-23, respectively (all in units of cm³ s^-1), based on the observed decay rates of ClONO2, N2O5, O3, and COCl2.Product analyses gave 0.82 +/- 0.07 for the yield of HNO3 in the ClONO2 + H2O -> HOCl + HNO3 reaction and 1.1 +/- 0.3 for the yield of HNO3 from the N2O5 + H2O -> 2HNO3 reaction.The quoted error represents one standard deviation of the measurement.An attempt was also made to monitor possible reaction products such as H2O2 for the O3 + H2O reaction, and CO2 or HCl for the COCl2 + H2O reaction.These results may be important in the elucidation of the springtime Antarctic ozone depletion over the past decade.The implication for NOx chemistry in the nighttime troposphere based on our results of the N2O5 + H2O reaction will be discussed.