A beer still (see Figure) is being used to separate ethanol from water at 1.0 atm. The saturated liquid feed flow rate is F = 840.0 kmol/h. The feed is 44.0 mol% ethanol. The saturated vapor steam is pure water with ratio of steam flow rate S to feed rate, S/F = 2/3. We desire a bottoms product that is 4.0 mol% ethanol. CMO is valid. Equilibrium data are in Table 2-1. a. Find the mole fraction of ethanol in the distillate vapor, yD,E. b. Find the number of equilibrium stages required. c. If the feed is unchanged and the S/F ratio is unchanged, but the number of stages is increased to a very large number, what is the lowest bottoms mole fraction of ethanol that can be obtained?

Feed Distillate, D kmol/h N stages Bottoms, B kmol/h Steam, S kmol/h