Crystalization

Chemistry 251 Experiment #3: Crystallization Winter 2010

Report due: Wednesday, January 20th

This will not be a formal report. Your answers to the questions below should be written out in paragraph form using complete sentences.

Part A (semimicroscale)

1. Include a data table with the following information:

A) Melting point range of impure sulfanilamide

B) Melting point range of purified sulfanilamide

C) Weight of impure sulfanilamide before crystallization

D) Weight of sulfanilamide after crystallization

E) Percent recovery

-Comment on the purity of your sample. Was the percent recovery good or bad? Why? You should discuss how the melting points of the purified sulfanilamide compared to the literature value? Be specific. Discuss possible sources of error for the experiment that would help account for your percent recovery or melting points (be specific).

2. Include a data table with the following information:

A) Weight of impure sulfanilamide at the start of the crystallization

B) Weight of pure sulfanilamide after crystallization

C) Weight of solid recovered from the mother liquor

D) Total weight of purified sulfanilamide and product recovered from the mother liquor

E) Calculated weight of sulfanilamide that remains in the mother liquor (Prelab calculation)

F) Melting point of the solid recovered from the mother liquor.

- Comment on any differences between the values obtained from letters A and D (weight that you started with and the total weight recovered) above. Should they be the same? Explain.

-Comment on any differences between letters C and E (amount of material found in the mother liquor to the amount you calculated in the prelab) above. Should they be the same? Explain.

- Compare the melting point of the solid recovered in the mother liquor to that of the crystallized sulfanilamide. Should they be the same? Explain....