$2.$ Consider the steady state mass transfer of ascorbic acid into the cytoplasm from the surrounding interstitial fluid through the outer membrane of a cell. The mass transfer coefficient on the intracellular space is estimated to be $4\mathrm{.}70$ x $10-8$ m$/$s$.$ The mass transfer coefficient outside the cell is approximately $1\mathrm{.}9$ x $10-7$ m$/$s$.$ The cellular membrane is $44$ thick, and the partition coefficient, K is $0\mathrm{.}50.$ The diffusivity of ascorbic acid through the cellular membrane is $7\mathrm{.}9$ x $10-6$ m$2/$s$.$ Assume that the concentration of ascorbic acid inside the cell is at $2\mathrm{.}3$M and in the interstitial space it is $23\mathrm{.}5$M$.$ NOTE: $1\mathrm{.}0\backslash$mu M $=1\mathrm{.}0$ x $10-6$ moles$/$liter $($M$)$

a$.$ Sketch and label this composite mass transfer problem. $(4$ points$)$

b$.$ Calculate the flux of ascorbic acid through the cell membrane. $(3$ points$)$

c$.$ Estimate the size of a cell $($make size assumptions clearly$)$ and calculate the rate of removal $($flow$)$ of ascorbic acid from the interstitial space. $(3$ points$)$