4. A student purified a 500-mg sample of phthalic acid by recrystallization from water. The published solubility of phthalic acid in 100 mL of water is 0.54 g at 14 oc and 18 g at 99 0C. (a) What is the smallest volume of boiling water the student could use to dissolve 500 mg of phthalic acid?