Postlab 4 - Name: Jeff Johnson Qz Section: BJ Lab Partner:...

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Unformatted text preview: Name: Jeff Johnson Qz Section: BJ Lab Partner: Kevin Hung Grading: 60 pts A. Starting Components (Fract. Crystallization #0) Step 3: Mixture before first crystallization 4.545 g 0.455 g Total mass of the sample mixture 5.000 g % Impurity (% Fe compound in the mixture) 10.01 % (This is your % impurity for Frac Crystallization # 0) Fract. Crystallization #1 Step 7: mass dry filter paper 0.47 g Step 10: 3.13 g 2.667 g 58.68 % Step 11: 0.112 g B. Fract. Crystallization # 2 (Re-crystallization) Step 6: mass dry filter paper 0.570 g Step 8: 1.42 g 0.853 g 18.77 % Step 9: 0.403 g mass KNO 3 mass (NH 4 ) 2 Fe(SO 4 ) 2 . 6H 2 O mass KNO 3 crystals + filter paper mass KNO 3 crystallized % KNO 3 recovered (% of amt in Step A.3.) mass KNO 3 to be analyzed for purity (~0.1 g) mass KNO 3 crystals + filter paper mass KNO 3 crystallized % KNO 3 recovered (% of amt in Step A.3.) mass KNO 3 to be analyzed for purity (~0.4 g) EXPERIMENT 4: I. Fractional Crystallization of KNO 3 with (NH 4 ) 2 Fe(SO 4 ) 2 .6H 2 O Impurity II. The Solubility Curve of KNO 3 DATA, CALCULATIONS AND GRAPHS Part I: Fractional Crystallization of KNO 3 with (NH 4 ) 2 Fe(SO 4 ) 2 . 6H 2 O Impurity PURPOSE AND METHOD Part I We wanted to verify that fractional crystallization is an effective method of isolating a large amount of target compound from a small amount of impurity. We dissolved a large amount of KNO 3 and a small amount of (NH 4 ) 2 Fe(SO 4 ) 2 . 6H 2 O in near-boiling water, then cooled the solution. The majority of the KNO 3 formed nearly pure crystals, which we extracted and recrystallized again. We calculated the % impurity after each step from the absorbance at 510nm and the molar absorbtivity of Fe. We also calculated the % of original KNO 3 remaining after each step....
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This note was uploaded on 05/08/2008 for the course CHEM 162 taught by Professor N. during the Spring '08 term at University of Washington.

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Postlab 4 - Name: Jeff Johnson Qz Section: BJ Lab Partner:...

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