5. A timed-release drug is dissolving in the intestine of a modern humanoid. As a steady-state approximation, we may assume that the drug is a rod of overall radius ro (m) and length L (m). The timed-release action is accomplished by putting an inert coating on the drug through which the drug diffuses with diffusivity Dab. At the inner edge of the coating, (ri), the composition (mole fraction) of the drug is Xao. On the outer surface, the digestive juices provide for mass transfer with a mass transfer coefficient of Kac (m/s). The amount of drug within the intestine can be approximated as Xgco a 0. Derive an expression for the steady-state, mole fraction profile of the drug through the coating. You may assume that the total concentration of all species within the coating is Ct and that the partition coefficient between the drug in the coating and the fluid is 1