A packed column is used to remove toluene from water by stripping with air. The water contains 60 ppm toluene (weight basis), and the concentration must be reduced to 2 ppm. The column will operate at 20°C and an average pressure of 1.1 atm. The equilibrium relationship is P_tol = 256x where P_tol = partial pressure of toluene, atm, in the gas phase, and x mol fraction of toluene in the liquid. 

(a) Determine the minimum air rate in g mol/min for a water rate of 100 L/min. 

(b) Calculate N_ox for an air rate twice the minimum. 

(c) Determine the packed height required if H_y = 0.7 m and H_x = 0.6 m.