The SO3 decay and H3NSO3 appearance were fit simultaneously to these equations with kf fixed at the value extrapolated from the lower temperature data. The reaction time was
calculated using the relationship t ) z/(1.7V) where z is the reaction distance and V is the average flow velocity. The rate coefficient for SO3 wall loss was fixed at the value measured
in the absence of NH3. This value was always within 10% of the diffusion-limited value, implying that the SO3 reaction probability with the reactor wall was greater than 10-3. The
nonlinear regression variables included the first-order H3NSO3