Application to the S IV -Ozone Reaction

We would like to use the tools developed above to determine if aqueous-phase reaction between ozone and S(IV) is limited by mass transport in a typical cloud. The subsequent analysis was first presented by Schwartz (1988). Typical ambient conditions that need to be examined include droplet diameters in the 10 to 30 pm range, cloud pH values in the 2 to 

FIGURE 11.9 Interfacial mass transport limitation. The several bands represent the onset (10%) of mass transport limitation for the indicated values of the accommodation coefficient a. The width of each band corresponds to the drop diameter range 3 to 100 /urn for Ma = 30 g mol (Schwartz, 1986). 

6 range, and cloud temperatures varying from 0 to 25 C. The reaction rate for the S(IV)-0, reaction is given by 

We need now to evaluate the pseudo-first-order coefficients for ozone and S(IV), which are included in the criteria of (11.85), (11.86), and (11.93). The effective first-order rate coefficient of ozone, l o, will be 

FIGURE 11.10 Examination of mass transport limitation in the S(IV)-03 reaction. Mass transport limitation is absent for points below and to the left of the indicated bounds (Schwartz, 1988). 

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