Caprolactam is industrially recovered and purified by extraction. A Chemical Engineering student needs to extract acetaldehyde in toluene. A solution of 9.3% acetaldehyde in toluene is to be extracted with water in a six stages co-current unit. If 32.1 kg water/100 kg feed is used, what is the mass of acetaldehyde extracted and the final concentration? The equilibrium relation is given by:

(kg acetaldehyde/kg water) = 2.27 (kg acetaldehyde/kg toluene).