Ninety-five percent of the acetone vapour in an 85 vol.% air stream is to be absorbed by counter-current contact with pure water in a valve-tray column with an expected overall tray efficiency of 50 %. The column will operate essentially at 20 ºC and 101 kPa pressure. Equilibrium data for acetone-water at these conditions are: Mole percent acetone in water 3.30 7.20 11.7 17.1 Acetone partial pressure in air, torr 30.00 62.80 85.4 103.0 Calculate:

Ninety-five percent of the acetone vapour in an 85 vol.% air stream is to be absorbed by counter-current contact with pure water in a valve-tray column with an expected overall tray efficiency of 50 %. The column will operate essentially at 20 ºC and 101 kPa pressure. Equilibrium data for acetone-water at these conditions are:
Mole percent acetone in water 3.30 7.20 11.7 17.1
Acetone partial pressure in air, torr 30.00 62.80 85.4 103.0
Calculate:
I. The minimum value of L’/V’, the ratio of moles of water per mole of air.
II. The number of equilibrium stages required using a value of L’/V’ of 1.25 times the minimum.
III. The concentration of acetone in the exit water.