The solubility of acetanilide in hot water (5.5 g/100 mL at 100) ...

[ec501234]

The solubility of acetanilide in hot water (5.5 g/100 mL at 100) is not very great, and its solubility in cold water (0.53 g/100 mL at 0) is significant. What would be the maximum theoretical percent recovery (first crop only) from the crystallization of 5.0 g of acetanilide from 100
  mL of water (assuming the solution is chilled to 0)?

Question 2

A student crystallized a compound from benzene and observed only a few crystals when the
  solution cooled to room temperature. To increase the yield of crystals, the student chilled the
  mixture in an ice-water bath. The chilling greatly increased the quantity of solid material in the
  flask. Yet when the student filtered these crystals with vacuum, only a few crystals remained
  on the filter paper. Explain this students observations.

[cascooper22]

Answer to Question 1

All 5 g of acetanilide would go into the hot water. On cooling, 0.53 g would remain in solution.
Therefore, 5 g  0.53 g = 4.57 g. The maximum percent recovery is 4.57 g/5 g = 0.91, or 91.

Answer to Question 2

The solid that appeared on chilling was actually solidified benzene (mp 5.5C), not the compound.

[ec501234]

Gracias!

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