4. [4 pts] In the class, we arrived the equation for CP modulus (CbCm=exp(kJw)) when assuming that the membrane is perfectly selective (Cp=0). Please derive an expression for the CP modulus (assuming that Cp=0 ) as a function of rejection, Jw, and k only (no concentration terms) (or of rejection and Pe where Pe=Jw/k). 5. [ 3 pts] In an ultrafiltration membrane unit used to concentrate a polymer solution, we have: - Pure water flux Jw1=100l/m2hr at 2 bars. - After being operated to concentrate the polymer solution for a given period of time, the water flux is recorded to be JW2=10l/m2. hr at 5 bars. What percentage of the total resistance to flow is caused by the membrane