Question

A solute with a partition coefficient of 4.0 in favor of chloroform is extracted from 10 mL of water. What is the total volume of chloroform is needed to extract 99% of the solute in three equal extractions? a. 9.1 ml 5.82.7 ml C. 27.3 mL d. 248 mL

Answer 1

Percent of solute to be recovered = 99 % Mass of solute present in aqueous phase after extractions = 1% Fraction of solute present in aqueous phase = 0.01 (K,V +V Fraction of solute present in water = q= aq/ where n= number of extractions = 3 q = fraction of solute present in aqueous phase = 0.01 Vo = Volume of the aqueous phase = 10 mL Vorg = Volume of the toluene = ? Ko = partition coefficient or distribution coefficient = 4.0 O Vaq 0.01 = ( 10 ) 0.01 = 4.0Vorg +10) take cube root on both sides 10 -= 0.215443 4V0 +10 . 10 = 46.41589 4Vorg +10 = 0.215443 4Vorg = 46.41589-10 = 36.41589 Vorg = 9.1 mL Option A is the right answer.