Methanol \(\left(\rho=791 \mathrm{~kg} / \mathrm{m}^{3}\right.\) and $\left.M=32
\mathrm{~kg} / \mathrm{kmol}\right)$ undergoes evaporation in a vertical tube
with a uniform cross-sectional area of \(0.8 \mathrm{~cm}^{2}\). At the top of
the tube, the methanol concentration is zero, and its surface is $30
\mathrm{~cm}$ from the top of the tube (Fig. P14-111). The methanol vapor
pressure is \(17 \mathrm{kPa}\), with a mass diffusivity of $D_{A B}=0.162
\mathrm{~cm}^{2} / \mathrm{s}$ in air. The evaporation process is operated at
\(25^{\circ} \mathrm{C}\) and \(1 \mathrm{~atm}\). (a) Determine the evaporation
rate of the methanol in \(\mathrm{kg} / \mathrm{h}\) and (b) plot the mole
fraction of methanol vapor as a function of the tube height, from the methanol
surface \((x=0)\) to the top of the tube \((x=L)\).