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.