Calculate the steady state flux of atomic hydrogen at 25°C through a steel vessel of wall thickness 4 mm given that the inside surface is kept saturated with hydrogen at a concentration of 4.5 moles/m3, the outside surface is exposed to the atmosphere. (The diffusivity of hydrogen in steel D0 = 0.1 mm2 s-1, Q = 13.5 kJ mol-1) A steady-state flux allows the application of Fick’s first law: J = -D(dC/dx)
If the vessel contains 20 moles of hydrogen, calculate the time taken to dissipate all of the hydrogen of that the vessel has a surface area of 3 m2.