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)?

90 %

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 %  

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