LAB REPORT_FractDistillation_Summer 2022

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University of North Florida *

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CHM-2210

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Chemistry

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Feb 20, 2024

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LAB REPORT SHEET and Calculation of % yield and % Composition of the ethanol- water azeotrope Name (Print):… Dalia Elkhatib … Partner’s name… Allie Larrimore and Lilly Amsden … Total points = 71 Note: Distillation using slow and gradual temperature change will give best results. Collect distillate between 78-86 o C at 70-75% Variac setting . Use a cotton, aluminum, or paper towel jacket around the fractionating column. Be patient. Procedure: (the experimental setup is the same as last week, except that there is dry West condenser (wide bore one) interposed between the distilling RB and the 3-way connector). Observations Record the temperature of the distilling liquid every minute beginning from the first drop, then recording temperature every minute until the temperature reached 90 o C (70-90 o C). 13 pt 1. Minute 0 (temperature when the first drop of condensate appears) = …… 65 … o C Minute 1 = …… 65 ……… o C Minute 2 = …… 66 ……… o C Minute 3 = …… 66 ……… o C Minute 4 = …… 66 ……… o C Minute 5 = …… 67 …..…. o C Minute 6 = ….. 66 ……… o C Minute 7 = ….. 66 ……… o C Minute 8 = …… 67 ……… o C Minute 9 = …… 67 ……… o C Minute 10 = …. 67 …….. o C Minute 11 = …. 67 …….. o C Minute 12 = …. 68 …….. o C Minute 13 = …. 68 …….. o C

Minute 14 = …… 69 …… oC Minute 15 = …… 69 …… oC Minute 16 = …… 70 …… oC Minute 17 = …… 73 …… oC Minute 18 = …… 74 …… oC Minute 19 = …… 74 …… oC Minute 20 = …… 74 …… oC Calculation of % composition (by mass) of the original ethanol-water mixture, and two fractions (collected distillate and the left-over fraction). (A) Calculation of % composition (by mass) of the original ethanol-water mixture by density Volume of the ethanol/water mixture used = 30.0 mL Mass of the empty 100-mL distilling R.B flask” = 47.48 g 1 pt Mass of the 100-mL distilling R.B flask + ethanol/water mixture = 75.01 g 1 pt Mass of the ethanol/water mixture by difference (show work) = 27.53 g 75.01 g – 47.48 g = 27.53 g 2 pt Density of the original ethanol-water mixture (show work) = 0.918 g/mL 2 pt 27.53 g / 30.0 mL = 0.9177 g/mL % Composition of the original ethanol-water mixture as read from the density- %composition table (given below) = 47.5 % ethanol 52.5 = % water 4 pt (45+50) / 2 = 47.5 100- 47.5 = 52.5 (B) Calculation of % composition (by mass) of the distilled mixture by density Mass of the “collecting 25-mL RB” flask = 25.04 g 1 pt

Mass of the collecting flask + distilled fraction including the azeotrope = 29.29 g 1 pt Mass of the distilled fraction including the azeotrope (show work) = 4.25 g 2 pt 29.29 g – 25.04 g = 4.25 g Volume of the distilled fraction including the azeotrope (use graduated cylinder) = 5.0 mL 1 pt Density of the distilled fraction including the azeotrope fraction (show work) = 0.85 g/mL 4.25 g / 5.0 mL = 0.85 g/ml 2 pt % Composition of distilled fraction including the azeotrope as read from the density- %composition table (given below) = 75 % ethanol 25 = % water 4 pt (C) Calculation of % composition (by mass) of the left-over fraction by density Mass of the distilling 100-mL RB” flask = 47.48 g 1 pt Mass of the distilling flask + left-over fraction = 70.75 g 1 pt Mass of the left-over fraction (show work) = 23.27 g 2 pt 70.75 g – 47.48 g = 23.27 g Volume of the left-over fraction (use graduated cylinder) = 25.0 mL 1 pt Density of the left-over fraction (show work) = 0.931 g/mL 2 pt 23.27 g / 25.0 mL = 0.9308 g/mL % Composition of distilled fraction including the azeotrope as read from the density- %composition table (given below) = 42.5 % ethanol = 57.5 % water 4 pt (40+45) / 2 = 42.5 100 – 42.5 = 57.5 =====================================================================

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Data analysis Table: Determination of % composition of ethanol by density measurement (ignore/delete this table for lab report) Density (g/ml) % (m/m) % (v/v) g/100 mL Density (g/ml) % (m/m) % (v/v) g/100 mL 0.98938 5 6.2 4.9 0.85564 75 81.3 64.2 0.98187 10 12.4 9.8 0.84344 80 85.5 67.5 0.97514 † 15 † 18.5 † 14.6 † 0.83095 85 89.5 70.6 0.96864 20 24.5 19.4 0.81797 90 93.3 73.6 0.96168 25 30.5 24.0 0.81529 91 94.0 74.2 0.95382 30 36.2 28.6 0.81257 92 94.7 74.8 0.94494 35 41.8 33.1 0.80983 93 95.4 75.4 0.93518 40 47.3 37.4 0.80705 94 96.1 75.9 0.92472 45 52.7 41.6 0.80424 95 96.8 76.4 0.91384 50 57.8 45.7 0.80138 96 97.5 76.9 0.90258 55 62.8 49.6 0.79846 97 98.1 77.4 0.89113 60 67.7 53.5 0.79547 98 98.8 77.9 0.87948 65 72.4 57.1 0.79243 99 99.4 78.4 0.86766 70 76.9 60.7 0.78934 100 100 78.9 PLEASE NOTE: Dispose of all chemicals in the appropriately labeled hazard waste containers. Halogenated waste, if any, must be disposed of in its designated container in the specified hood. All glassware must be washed with soapy water, then DI water, and finally rinsed with acetone to wash off the organic residue. The clean glassware should be dried and put back into the tray or its original place. Other pieces of equipment (ring stands, clamps, hot plate, stir bars, heating mantels, etc) must be

returned to their proper locations. Did the experiment go as planned? One mistake we made during the experiment was packing the copper too tightly into fractionation column, which prevented the solution from further travel throughout the apparatus. This was solved by removing the copper and replacing it with coils more loosely packed. There may have also been an issue with our thermometer, as the temperature appeared to fluctuate between increasing and decreasing at one point, but whether or not this was in a mistake in our own perception is unclear. Due to time constraints, we were unable to replace the thermometer, but we will in future experiments if this occurs again. 10 pt (you must write something here even if your experiment went perfectly well. If not, describe what happened and how would you improve your procedure if you were given another chance to do the experiment) If not, what were the problem and how did you solve them? Guidelines for pre-lab quiz Review my narrated PowerPoint presentation or study this experiment in the manual. Post-lab questions 1. What is an azeotrope, or an azeotropic mixture? 3 pt An azeotrope is a mixture of two components that cannot be easily separated and act as a pure substance, maintaining their composition and boiling point during distillation. 2. What is the purpose of packing the fractionating column with copper turnings/spirals? 3 pt The purpose of the packed copper is to allow more surface area for condensation of the water-ethanol vapors. This results in a series of “mini distillations,” or theoretical plates, which separate the two compounds more efficiently. 3. State Raoult’s Law in mathematical form and define different terms in it.

P A = P 0 A X A 3 pt P A = vapor pressure of solution P 0 A = vapor pressure of the pure solvent X A = mole fraction of the solvent 4. What is meant by “Fractionating column efficiency? It is the number of theoretical plates that the fractionating column can generate. 3 pt 5. What is meant by “theoretical plate” of a fractional distillation column? 3 pt A theoretical plate is a “mini distillation,” or individual occurrence of vaporization and condensation, that takes place within the fractionating column. 6. Is the ethanol/water azeotrope distillation a result of negative deviation or positive deviation from Raoult’s law? It is the result of a positive deviation. This is because its boiling point is lower than that of its constituents. 1 pt

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