Recrystallization Exercises:

1. What is the process of "seeding", as it applies to recrystallization? What purpose does it serve?

2. How can the purity of a recrystallized solid be assessed?

3. Why is it important to:

a. avoid the inhalation of organic solvents?

b. know the position and procedure of operation of the nearest fire

extinguisher when employing diethyl ether as a recrystallization solvent?

c. use a fluted filter paper for hot filtration

4. Briefly define the following terms:

a. melting‑point range

b. mixture melting point

c. melting point

5.Indicate which of the following statements is true (T) and which false (f) by putting a

check mark in the appropriate space

T F

_ _ a. An impurity raises the melting point of an organic compound.

_ _ b. The sample should not be packed tightly into a capillary melting‑

point tube.

6. What is the preferred technique for accurately determining the melting point of an

unknown compound in a minimum length of time?

7. How does measuring a mixture melting point help in determining the possible identity of

two solid samples?

8. What is the approximate rate at which the temperature in the Mel-temp should be

increasing at the time the sample undergoes melting?

9. Briefly describe the technique for packing a capillary melting point tube.