The data in Table 11.P2 were obtained for the recovery of methyl ethyl ketone from water by solvent extraction. 500 kg/hr of an aqueous 18 percent by weight ketone solution is to be processed, with 85 kg/hr of ketone removed.
a. Find the minimum flow rate of each solvent required to effect the separation. State any assumptions carefully.
b. Find the number of equilibrium stages required for each solvent if (i) 1.2 times and (ii) 1.5 times the minimum solvent is to be used.

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Table 11.P2. Equilibrium data for methyl ethyl ketone in water and two organic solvents. Data of M. Newman, C. B. Hayworth, and R. E. Treybal, Industrial & Engineering Chem., 41, 2039-2043 (1949). Ketone 18.15 12.78 9.23 6.00 2.83 1.02 18.10 13.10 9.90 7.65 5.52 3.64 Water-rich phase (wt%) Solvent 0.11 0.16 0.23 0.30 0.37 0.41 0.05 0.08 0.12 0.16 0.21 0.28 p (kg/m³) Ketone 1,1,2-Trichloroethane as solvent 75.00 58.62 44.38 31.20 16.90 5.58 970 980 990 990 990 1,000 Chlorobenzene as solvent 75.52 58.58 43.68 29.65 17.40 8.58 Solvent-rich phase (wt %) Solvent 970 980 980 990 990 990 19.92 38.65 54.14 67.80 82.58 94.42 20.60 39.28 55.15 69.95 82.15 91.18 p(kg/m³) 890 970 1,006 1,114 1,126 1,136 860 900 950 990 1,030 1,060