Question

If 50 mg of phenacetin were dissolved in 100 mL of water, how much will be extracted using one 100 mL portion of ether? Show your calculations

Answer 1

Phenacetin is the common name for 1-acetamido -4- ethoxybenzene. It is slightly soluble in water and more soluble in Diethyl ether.

Distribution coefficient K (water : diethyl ether) = 0.0167

90 % of phenacetin requires to be extracted. So fraction of phenacetin remaining = 0.1

Volume of water V1 = 100 mL

Fraction remaining after one extraction = V1 / ( V1 + KV2)

0.1 = 100 mL / ( 100 mL + 0.0167 (V2))

10 + 0.00167 V2 = 100

V2 = 90 / 0.00167

= 53892.22 mL or 53.89 L