Mass transfer

SO, (A) is transferring at a steady-state through non-diffusing oxygen Oz (B) in a metal conduit 2 meters long at 10 bars and 598 K as shown below. The cross-section of the conduit is rectangular and tapers uniformly from an area of 300 mm by 400 mm to an area of 300 mm by 200 mm. The partial pressure of SO, is measured as 0.22 bar and 0.055 bar at two ends. Calculate the molar flux (NA) at the midpoint of the conduit (Z=L/2). The molecular diffusivity (DAR) of SO2 in O2 at 1 bar and 25 C is 2.25 x 10 m/sec