19.1-21. effect of a slow reaction rate on diffusion. gas a diffuses from point 1 to a catalyst surface at point 2, where it reacts as follows: 2a → b. gas b diffuses back a distance δ to point 1. derive the equation for na for a very fast reaction using mole fraction units xa1, and so on. for dab = 0.2 × 10–4m2/s, xa1 = 0.97, p = 101.32 kpa, δ = 1.30 mm, and t = 298 k, solve for na. do the same as in part (a) but for a slow first-order reaction where k1′ is the reaction velocity constant. calculate na and xa2 for part (c) where k1′=0.53×10−2m/s.