While performing the experiment, a project student collected ethanol (C2H5OH) in an open beaker and kept it in a fume hood with continuous air circulation. The project student forgot to put a lid on the open beaker and left the lab to take rest. The high purity ethanol was left open to evaporate. A gentle flow of dry air at 35C and 1 atm is facilitated by fume hood across the mouth of the beaker so that evaporated ethanol is carried away after it transfers through a stagnant air layer in the beaker. The initial liquid level is at 1 cm from the mouth of the beaker. Consider that the liquid temperature is constant at 35C throughout.

(a) Find the diffusion coefficient of ethanol vapors in air at 35C and 1 atm.

(b) Calculate the initial rate of evaporation of ethanol as a molar flux in appropriate units

(c) Develop a mathematical expression for initial mole-fraction profiles and plot with minimum of 5 data points (from the mouth to liquid surface). Hint: Consider steady state molar diffusion of ethanol through stationary air phase.

(d) Project student realizes about the experiment with ethanol after 12 hrs and returns to the lab. What would be the liquid ethanol level after 12 hrs?

Data: The vapor pressure of ethanol at 35C is 13.3 kPa. The diffusion coefficient for ethanol in air at 0C and 1 atm is 1.02 10-5 m2/s. The density of ethanol liquid at 35C is 0.7809 g/cc.