I Need help with D, E and F! Please

(30 points) A transdermal patch for drug delivery contains a 0.05M solution of the drug in a capsule 2mm thick and 3cm in diameter. This patch is applied by first covering the skin at the application site with a 250 um polymer film and placing the patch in direct contact with the film. The drug diffusion coefficient in solution is 5.4 X 10-6 cm/s; in the polymer film it is 1.8 X 10-7 cm-/s. The equilibrium concentration in the polymer phase is 0.6x that in solution. The drug is rapidly absorbed by the skin and so the concentration at the polymer skin interface is zero. Remember that the drug is the only mobile species in this system. (a) Draw diagrams showing the various phases and the molar concentration gradient of the drug right after application of the patch (t=0) and after equilibration (t=t'). (b) Calculate the mass transfer coefficients in the capsule, across the polymer film and the effective mass transfer coefficient across the interface. (c) What fraction of the drug in the capsule is absorbed in the first 2 hours? (d) Plot the hourly drug absorption fractions over 5 hours. (e) At what time will the rate of drug delivery be only half the initial rate? (f) When would the delivery rate approach zero