Question

The distribution coefficient of styrene distributed between ethylbenzene and ethylene glycol at 25°C is 0.19 mass fraction in the ethylene glycol phase per mass fraction in the ethylbenzene phase. One hundred grams of pure ethylene glycol is added to 120 g of a mixture containing containing 73 wt% ethylbenzene and 25% styrene, and the resulting blend is allowed to equilibrate. How much styrene transfers to the ethylene glycol phase, assuming that ethylene gylcol and ethylbenzene are immiscible?

Answer 1

Kd = styeren in ethyl benzene/ styrene on glycol = 0.19

100 g   ethylene glycol

ethyl benznen mass = ( 73/100) x 120 = 87.6 g

styrene mass = ( 25 /100) x 120 = 30 g

Now   let m be mass of styrene passed to glycol layer.

then mass in ethyl benzene = 30 - m.

Hence Kd = 0.19 = ( 30-m) / ( 87.6) /   ( m/100)

0.19 = ( 100/87.6)    x ( 30-m / m )

0.16644 m= 30-m

m = 25.72 g

thus mass transferred to glycol layer is 25.72 grams