Question 5. Consider a case of 1D - steady state diffusion mass transfer, without any homogenous chemical reaction. Here, convection mass transfer does not occur. For a hollow sphere with internal radius r1 and external radius r2, the species diffusion resistance is 4DAB1(r11r21). Using the molar rate equation, the terms can be arranged to obtain a species diffusion resistance: Rm,dif=NA,x(CA,s1CA,s2)=DABAL. For this problem, hydrogen gas is contained in a spherical tank at 25C, the tank is made of 4mm thick steel and the outer diameter is 150 mm. The diffusion coefficient of hydrogen in steel is known to be 1.91013m2s1. At the interior surface of the sphere, the molar concentration of hydrogen is 2kmolm3. If we assume that there is no hydrogen on the outer surface currently, then what is the initial rate of mass loss of hydrogen by diffusion through the spherical wall