5. As shown in Figure 4, one can draw a control volume on a differential volume on the shell side of the separator. Write out the mass balance on oxygen for this control volume and transform it into a differential equation, but do not solve. Can you solve for x(z) and y(z) analytically? 6. Given the difficulty of solving the full set of governing equations outlined in Question 5, we will develop a simpler model for approximate analysis. Consider again the control volume depicted in Figure 4. Define ym as the oxygen mole fraction in the gas entering the control volume through the membrane at z. What is the difference between ym and y ? Assume that y is constant within the control volume, i.e. perfect radial mixing. Figure 4: scemanc o coumer-curem memrane-separai um empnasizmg a anerential control volume over which an oxygen mass balance is applied on the shell side. Note that only the oxygen fluxes are labeled