1) gas a diffuses through a planar gas film (z1) to a flat catalyst surface (z2), where it reacts as follows: 1� → 3�. gas b diffuses back a distance � to the point (z1). a) derive the eq. for na for a very fast reaction using ya1, ya2, concentration (ct), and �. b) for dab = 4.3 x 10-4 m2 /s, ya1=0.83, pt=101 kpa, �= 95 µm, 625 k, solve for na (kg mol/s. m2 ). c) repeat part (a) but for a first-order reaction where k’1 is the reaction rate constant (assume units of k1’ of m/s). d) calculate na and ya2 for part (c) where k’1 =0.05 m/s. (note: this part requires a few iterations by trial and error