Name: Ryan D’Alleva Unknown Number(s): 9
Experiment Title: Recrystallization
Section Day/Time: Thursday/1:30-5:25 If Make-Up, lab performed on:_______________
Teaching Assistant: Enes Buz
Lab Technique: Leave this section blank in your report. But, make sure to tell Gradescope
it is on page one of your lab report. Your TA will assign the technique points when they
grade the post-lab. Do not delete this text.
Purpose: The purpose of this experiment is to purify organic compounds which are solid at room
temperature through the recrystallization process.
Pre-Lab: Leave this section blank in your post-lab report. But, make sure to tell Gradescope it
is on the appropriate page. Your TA should have graded the prelab before you began the
experiment. They will assign the awarded points for the prelab with the report. Do not delete
this text.
In-Lab Entries and Observations: The recrystallization experiment was performed on
September 19, 2019. Unknown #9 was assigned in the laboratory. The first step in the
experiment required conducting solvent tests to determine the best solvent for recrystallizing the
unknown compound––a solvent that has high solubility at high temperatures and low solubility
at low temperatures. This was done by adding 0.25 milliliters of each solvent to (different) test
tubes with 10 milligrams of the unknown compound, and then bringing the solution to near or at
a boil. Then, if the compound dissolved, it was allowed to cool to begin crystallization. Just two
of the given solvents were found to be unsuitable for the unknown compound, as the hexane
solution was insoluble at all temperatures and the 70% ethanol solution was soluble at all
temperatures. Therefore, these two solvents were not considered for use. Water, toluene, ethanol,
and methanol all dissolved the compound whilst boiling and allowed for the formation of crystals
upon cooling. Toluene notably produced large crystals very quickly, whereas ethanol and
methanol formed crystals very slowly. Once the solvents were tested, the experiment moved
towards the macro scale recrystallization of phthalic acid.
0.254 grams* of phthalic acid were weighed out and placed into an Erlenmeyer flask.
Through pipet drops, boiling water was added while simultaneously heating the flask. This was
done until complete dissolution had taken place, which took approximately 5 minutes. Once this
occurred, the flask was allowed to cool to room temperature, and then placed into an ice bath to
further induce crystallization. The crystals were separated from the solution via suction filtration,
and then stored away to dry.
*The procedure required 0.325 +/- .01 grams to be used, but this was misread and 0.254 grams
were used instead.
