Question

The solubility of acetanilide in hot water (5.5 g / 100mL at 100 o C) is significant and its solubility in cold water (0.53 g / 100mL at 0 oC) is not very great.

What would be the maximum theoretical precent recovery (first crop only) from the crystallization of 3.4 g of acetanilide from 65 mL of water (assuming the solution is chilled to 0 o C)?

Answer 1

90 %

Step-by-step explanation:

The solubilities at 100 ºC and 0 ºC are given per 100 mL of water, so we need to calculate the solubilities for 65 mL :

5.5 g/ 100 mL x 65 mL = 3. 58 g @ 100 ºC

0.53 g/ 100 mL x 65 mL = 0.34 g @ 0 ºC

3.4 g of acetanilide will dissove at 100 ºC and when cooled to 0 ºC it will crystallize and the amount remaining in solution will be determined by the solubilty at this temperature:

acetalinide in solution = 0.34 g

acetalinide crystallized = (3.4 - 0.34) g = 3.06 gtheoretical percent recovery = 3.06 g / 3.4 g x 100 = 90 %