A liquid feed at the boiling point con taine 33 mol % ethanol and 96.7 mol % water and enters the top tray of a stripping tower. Saturated steam is injected directly into liquid in the bottom of the tower. The overhead vapor which is withdrawn contains 99% of the alcohol in the feed. Assume equimolar overflow for this problem. Equilibrium data for mole fraction of alcoh are as follows at 101.32 kPa abs pressure (1 atm abs): x y x y
0 0 0.0296 0.250
0.0080 0.0750 0.033 0.270
0.020 0.175

Required:
a. For an infinite number of theoretical steps, calculate the minimum steam needed per mole of feed.
b. Using twice the minimum moles of steam, calculate the number of theoretical steps needed.