Dissolution
1. Place 1.5 g of impure benzoic acid in an 250-mL Erlenmeyer flask equipped for magnetic stirring or with boiling stones.
2. Measure 70 mL of water into the graduated cylinder and add a 60-mL portion of it to the flask. Heat the mixture to a gentle boil and continue adding water in 0.5-mL portions until no more solid appears to dissolve in the boiling solution. (10 minutes or more)
3. Record the total volume of water used; no more than 10 mL should be required.
Caution: Because the sample may be contaminated with insoluble material, pay close attention to whether additional solid is dissolving as you add more solvent; if it is not, stop adding solvent.