KhangExperiment4

KhangExperiment4 - Experiment 4: The Extraction and...

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Unformatted text preview: Experiment 4: The Extraction and Recrystallization of Benzoic Acid TD Khang 02/22/12 Emilie Mainz Chem 241L, Section 410, Morehead 404 Pledge Results and Calculations. Initial Mass of Benzoic Acid 0.52 grams Mass of Filter Paper 0.25 grams Mass of Filter Paper + Benzoic Acid 0.61 grams (incorrectly weighed as 1.31 g) Mass of Recovered Benzoic Acid 0.36 grams Table 1. Masses involved with Recrystallization of Benzoic Acid Sample calculation for Mass of Recovered Benzoic Acid in Recrystallization: (Mass of Filter Paper + Benzoic Acid) Mass of Filter Paper = Mass of Recovered Benzoic Acid 0.61 grams 0.25 grams = Mass of Recovered Benzoic Acid 0.35 grams = Mass of Recovered Benzoic Acid Initial Mass of Benzoic Acid 0.33 grams Mass of Beaker 50.47 grams Mass of Beaker+ Benzoic Acid 50.69 grams (incorrectly weighed as 51.39 g) Mass of Recovered Benzoic Acid 0.22 grams Table 2. Mass data involved with Extraction Process of Benzoic Acid Sample calculation for Mass of Recovered Benzoic Acid in Extraction Process: (Mass of Beaker + Benzoic Acid) Mass of Beaker = Mass of Recovered Benzoic Acid 50.69 grams 50.47 grams = Mass of Recovered Benzoic Acid 0.22 grams = Mass of Recovered Benzoic Acid Melting Point of Crude Benzoic Acid 118.9C 124.5C Melting Point of Recrystallized Benzoic Acid 121.9 o C 126.9 o C Melting Point of Extracted Benzoic Acid 122.3 o C 126.0 o C Literature Melting Point Value of Benzoic Acid 122.13C Table 3. Melting Point Values Mass of Initial/Impure material Mass of Recovered/Pure material Percent Recovery Recrystallization 0.520 g 0.360 g 69.2% Solvent-solvent 0.330 g 0.220 g 66.7% extraction Table 4. Percent Recovery Data Percent Recovery Calculation for Recrystallization: The same calculation was used to find the percent recovery for the acid-base solvent-solvent extraction. Discussion . Recrystallization works by taking advantage of the fact that different solutes have different solubility factors, and the solubility of the solvent is directly affected by the temperature of the solvent, and the fact that a crystal lattice is formed. When the impure benzoic acid is dissolved into water, the impurities and the benzoic acid separates (at a high temperature). At the higher temperature (almost at boiling), the solute (benzoic acid) becomes highly soluble to the solvent. By allowing it to cool slowly, the solution becomes an over saturated solution. In an attempt to help maintain its saturated state, the solution gradually releases its hold on the benzoic acid ions. As they are released, a crystal seed is form, and the acid slowly builds a crystal lattice on this seed. If the crystal lattice is allowed to form slowly, it will only contain benzoic acid (not the impurities) because of the shape of the lattice being formed. Once the crystals form, they will naturally kick out the impurities. All that is left is to drain the water (containing the impurities) away from the crystal lattice, and this process was achieved using a filtration vacuum. away from the crystal lattice, and this process was achieved using a filtration vacuum....
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This note was uploaded on 02/29/2012 for the course BIOC 107 taught by Professor Staff during the Spring '12 term at UNC.

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KhangExperiment4 - Experiment 4: The Extraction and...

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