Date of Experiment:6/10/13 Name:
I. Title: Isolating Caffeine from Tea
II. Objective: The objective of this lab was to extract caffeine from instant tea and purify it using sublimation.
III. Procedure: Change: We did not calculate percent recovery or perform step A.
IV. Results & Discussion:
After we placed the tea, NaOH and dichlormethane in the flask it was placed on the magnetic stirrer for approximately 10 minutes. It was clear that layers of solution were forming and were not creating an emulsion. We used a gravity filter to separate the two phases however due to the humidity in the classroom the filter got clogged and we only were able separate a portion (around ¾) of the two phases. The evaporation of the dichloromethane went quick; we streamed air over it and the bottle became very cold while the dichloromethane was evaporating. Tiny crystals were visible during the evaporation process. During the sublimation process we were able to see the vapor in the flask while heat was being applied and the vacuum filtration was on. The crystals that were seen on the flask during the evaporation transferred onto the cold finger. After there were no more crystals being formed quickly we scrapped them of the cold finger before condensation formed on the test tube and made out caffeine extract impure. We weighed the weigh boat prior to scrapping crystals into it, its weight was 1.801 grams. It weighed