Question $2$: Steady State Diffusion of component A through a stagnant $E$ and $F$ in a vertical tube$(25)$

In a vertical tube, liquid $A$ is at $z=z1,$ as shown in the figure below, and is diffusing through a stagnant gas $E$ and $F$ in the evaporation process. In order to calculate the flux of $A$ in the tube follows the steps below. IF the concentration of $A,$ is $xa=0\mathrm{.}015$ at $z=0,$ and $xa=0\mathrm{.}025$ at $Z=z2.$ For this mole fraction determine the concentration in the tube as follows:

Setup the above coordinate system and draw the problem in rectangular coordinates.

Write the boundary conditions for $E$ and $F,$ explaining your answer.

Write down the relevant balance equations in vector form for $E$ and $F$ components, and simplify the terms indicating your reasons. Simplify the scalar form indicating your reasons.

Write the Stephan$-$Maxwell constitutive equation for $E$ and $F$ for the concentration in the $z$ direction and substitute into step $3$ to obtain a differential equation for the concentrations of $(E$ and $F)$

Solve the above equation for $E$ and $F,$ and determine the concentration of A buy mole balance.

Determine the flux of $A$ at the surface of the liquid

Determine the Log Mean average concentration of $A$ in the tube