Phthalic acid has a solubility of approximately 18g per 100 ml of water at 100°c and 0.62g per 100 ml of water at 25°c. what is the minimum volume of water needed to recrystallize 50 mg of phthalic acid? how much phthalic acid will remain in solution after recrystallization?

The minimum volume of water needed is 0.28 mL. The solution will have

1.7 mg of phthalic acid remaining in solution.

At 100 °C

Volume of water required = 50 mg HPh * (100 mL water/18 000 mg HPh)

= 0.28 mL water

At 25 °C

Mass of HPh in solution = 0.28 mL water * (620 mg HPh/100 mg water)

= 1.7 mg HPh