2 The distribution coefficient between methylene chloride an

2) The distribution coefficient between methylene chloride and water for solute Y is 16. An amount of 85.0 g of Y is dissolved in 160 mL of water. a) What weight of Y would be removed from water with a single extraction with 160-mL of methylene chloride? Report to 1 decimal place. b) What weight of Y would be removed from water (the original solution) with two successive extractions with 80-mL portions each of methylene chloride? Report to 1 decimal place

Solution

Y=distribution coefficient = 16= {mass of Y/ volume)organic phase}/ (mass of Y/volume) aqueous phase

let x= grms of Y in organic phase

hence 16= x/160/(85-x)

16= x/(85-x)

16*85= 17x

x= 16*85/17=80 gm

80 gm of Y would be removed from water.

2. when two stages are used each using 80 ml for each stage

x/80/(85-x)/160= 16, where x=gm of Y extracted

x/(85-x)= 8

x= 85*8-8x

9x= 85*8, x=75.6 gm, x= Y extracted in the 1st stage.

Y remaining in the second stage= 85-75.6= 9.4 gm

for the second stage, let x= gm of y extracted

hence 16 = x/80/(9.4-x)/160

x/(9.4-x)= 8

x= 8*9.4-8x

9x= 8*9.4

x= 8.35

total of Y extracted= 75.6+8.35= 83.95 gm