A student purified a 500-mg sample of phthalic acid by recrystallization from water. The published solubility of phthalic acid in 100mL of water is 0.54 g at 14C and 18 g at 99C. The smallest volume of boiling water the student could use to dissolve 500 mg of phthalic acid is 2.778 mL of water.