Abstract: Experiment 55 consists of devising a separation and purification scheme for a three component mixture. The overall objective is to isolate in pure form two of the three compounds. This was done using extraction, solubility, crystallization and vacuum filtration. The experiment was carried out two times, both of which were successful.
Background Information: This experiment combined all the knowledge of the previous labs performed throughout the semester. An unknown mixture containing an organic acid or base and an organic neutral compound in nearly equal amounts needs to be separated to its separate components. An understanding of solubility, extraction, crystallization and vacuum filtration is necessary in order to
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The procedure remained nearly the same with the following changes. When isolating the neutral compound from the acid, the aqueous layer (top) was the acid and the organic layer (bottom) was the neutral compounds. To the acid layer, 6M HCl was added until solid stopped forming, and then methylene chloride was added until the solid dissolved. Once the methylene chloride was evaporated off, the acid was in pure state. The neutral layer was dried over anhydrous sodium sulfate, and then solvent was evaporated off. Tiny amounts were used to test for proper solvent for crystallization. The solvents used were methanol and 95% ethanol. The crystallizion was carried out using methanol and then the crystals were isolated using vacuum filtration.
Acid (benzoic acid)
Melting point: 85-87°C