Question

1-Solute A has a K = 3 for an extraction between water (phase 1) and benzene
(phase 2).
If 100 mL of a 0.01M solution of A in water is extracted one time with 500 mL
benzene, what fraction will be extracted?
2-For the same example, what fraction will be extracted if 5 extractions with 100
mL benzene each are used (instead of one 500 mL extraction)?

Answer 1

1)

first determine the fraction not extracted (fraction still in phase 1 ,q)

q = (V1 / V1 + K V2)^n

     = (100 mL / 100 mL + 3 x (500 mL)^1

    = 0.062

    = 6.2 %

the fraction extracted = p = 1 -q

p = 1 - 0.062

p = 0.938

p = 93.8 %

2)

determine the fraction not extracted (fraction still in phase 1 ,q)

q = (V1 / V1 + K V2)^n

     = (100 mL / 100 mL + 3 x (100 mL)^5

    = 0.00098

    = 0.98 %

the fraction extracted = p = 1 -q

p = 1 - 0.00098

p = 0.99902

p = 99.902 %

fraction will be extracted = 99.902 %