Question

2. A thick, impermeable pipe 3-cm in diameter and 10-cm long contains a gas that includes 0.5x1020 Nitrogen atoms per cm3 and 0.5x1020 Hydrogen atoms per cm3 on left side of an iron membrane. Gas is continuously introduced to the pipe to assure a constant concentration of Nitrogen and Hydrogen. The gas on the right side of the membrane includes a constant 1018 N atoms per cm3 and 1018 H atoms per cm?. The entire system is to operate at 700°C (973 k). Membrane iron has a BCC structure. Determine the minimum and maximum thicknesses (Ax=?) of the iron membrane that will allow no more than 1% of the Nitrogen to be lost through the membrane each hour while allowing 90% of the Hydrogen to pass through the membrane per hour Ax 0.5x1020 N atoms/cm3 1018 N atoms/cm3 0.5x1020 H atoms/cm3 1018 H atoms/cm3 3-cm 10-cm 10-cm DN 0.0047 exp(-18,300/kT) DH 0.0012 exp(-3600/kT) Hint: Use Fick's First Law