We are recovering pyridine from water using chlorobenzene as the solvent in a countercurrent extrac- tor. The feed is 35 wt% pyridine and 65 wt% water. Feed flow rate is 1000 kg/h. The solvent is pure. The desired outlet extract is 20 wt% pyridine and the desired outlet raffinate is 4 wt% pyridine. Operation is at 25C and 1 atm. Equilibrium data are given in Figure 2. a) Find the number of equilibrium stages needed. b) Determine the solvent flow rate required in kg/h. 1 0.9 Pyridine-water-chlorobenzene system 25C, 1 atm 0.8 0.7 0.6 Wt fraction of pyridine 0.5 0.4 0.3 0.2 0.1 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 wt fraction of water Figure 2: Equilibrium data for pyridine-water-chlorobenzene system at 25 C and 1 atm [dotted lines are the tie-lines]