Experiment_4__Recrystallization_of_Benzoic_Acid_Lab_Report Experiment_4

Experiment_4__Recrystallization_of_Benzoic_Acid_Lab_Report Experiment_4

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EXPERIMENT 4: RECRYSTALLIZATION OF BENZOIC ACID (FORMAL) Introduction: ___9__ / 15 pt Procedure: ___6__ / 7 pts Data and Results (6 points each) : __20__ / 24 pts Table of Masses from Recrystallization (Part I) containing the initial mass of benzoic acid, the mass of the filter paper, the mass of the filter paper + benzoic acid, and the mass of the recovered benzoic acid. Table of Masses from Acid-Base Extraction (Part II) containing the initial mass of benzoic acid, the mass of the beaker, the mass of the beaker + the mass of benzoic acid, and the mass of recovered benzoic acid. Table of Melting Points - Melting points of crude and purified material along with literature value melting point for benzoic acid. Table of Percent Recovery Data Sample Calculations: ___5__ / 5 pts Percent recovery calculation. Discussion ___15___ / 20 pts Compare and contrast the two different purification procedures used in this experiment. Compare the percent recovery of benzoic acid obtained from the two different methods used in this experiment and discuss your findings. Compare the melting point obtained from your recrystallized benzoic acid to the melting point obtained from the impure benzoic acid sample you started with and to the melting point for benzoic acid reported in the literature. Discuss your findings with regards to the goals of this experiment. Observations from the experiment. Did results agree with what would be predicted? Is the discussion section cohesive and well written. 4 Questions: (6 points each) __22__ / 24 pts
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Style (organization, neatness, proper formatting etc…) ___5__ / 5 pts Other Deductions (i.e., late lab report, incorrect formatting, etc…) - _______ Score __82__/ 100 pts
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Experiment 4: The Extraction and Recrystallization of Benzoic Acid Pledge Introduction: The objective of the experiment was to use recrystallization and acid-base extraction to purify a crude sample of benzoic acid and to test the purity by comparing the melting points of the crude sample with the purified samples. The purification of crude samples is meant to
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remove impurities such as excess reagents, synthetic by-products and other contaminants (1). The process of recrystallization involves dissolving an impure solid in a hot solvent and then slowly regenerating a pure solid via crystallization. This process works because different compounds have different solubility characteristics in different solvents. Recrystallization beings with dissolving the impure solid in a hot solvent at a high temperature, which is then followed by very slowly cooling the solution, isolating the formed crystals by vacuum filtration, and ends with vacuum drying the crystals (1). The acid-base extraction method on the other hand uses the acid-base properties of
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This document was uploaded on 11/04/2011 for the course CHEM 241 at UNC.

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Experiment_4__Recrystallization_of_Benzoic_Acid_Lab_Report Experiment_4

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