Boiling Point Lab report PDF

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This is a lab report that was completed and submitted to TA. I received 100% on the assignment....

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Boiling Point, Refractive Index, and Introduction to Gas Chromatography February 27th, 2018 Laboratory Partners: Samantha and Mackenzie

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Goals: Correctly determine the boiling point of an unknown liquid Measure the refractive index of an unknown Use the gas chromatogram to determine the mass percentage of a mixture and the relative detector response factors.

Procedure: D2: Determining the Boiling Point of an Unknown Liquid 1. Wear goggles and lab coat 2. Obtain unknown liquid, boiling chip, craig tube, clamps, heat block, thermometer, nomograph. 3. Record unknown liquid number in lab notebook. 4. Add 0.3-0.5 mL of unknown and boiling chip to test tube. 5. Clamp tube in heat block. 6. Suspend thermometer so the end of the bulb is 0.5 cm above the liquid. 7. Heat slowly 8. Once the temp. is stable, record the temperature in lab notebook. 9. Identify the unknown liquid and record in the lab notebook. 10. Calculate the percent error between the obtained boiling point and the actual boiling point. (record) E1: Measuring the Refractive Index of an Unknown Liquid 1. Get sample of unknown and record the number in notebook. 2. 4 drops of unknown between plates of the refractometer 3. measure the refractive index and the ambient temp. (record in notebook) 4. apply correction factor to refractive index if temp isn’t 20 degrees Celsius 5. Identify the unknown liquid 6. Calculate percent error and record J1: Determining Relative Detector Response Factors in GC 1. Inject 1-2L of the mixture. 2. Record column temp, flow rate of carrier gas, polarity of the column. 3. Adjust attenuation so all peaks fit on paper. 4. Measure area of each peak and record 5. Inject 1-2L of 1-butanol, 2-butanone, and methyl acetate 6. Compare retention times and record 7. Find relative mass percent for each

8. Find relative detector response factor for each compound. J2: Determining Mass Percent of a Mixture Using GC 1. Obtain sample and record the number in notebook. 2. Inject 1-2L of mixture and record the chromatogram reading 3. Record column temp, polarity and flow rate 4. Find the area of each peak 5. Identify the compounds using the peaks. 6. Calculate the corrected area for each. 7. Determine the mass percent Observations:  Our unknown boiled at 71 C and we determined that it was Ethyl Acetate.  Covering our boiling substance with aluminum foil allowed it to trap the heat and come to a boil more quickly.  The ambient temperature our of substance in E1 was 24C and we determined that it was Hexane. Results: D2: Unknown F Boiling Point: 71 C Identity: Ethyl Acetate Percent error: -7.9% E1: Unknown #6 Ambient Temperate: 24 C Refractive Index: 1.3767 Identity: Hexane Percent error: .116% J2: 1-Butanol B.P. 117C, F = 1.19 2-Butanone B.P. 82C, F = 0.99 M.A. B.P. 58C , F = 0.84 Normal area %: Peak 1: 45.78% Peak 2: 28.56% Peak 3: 25.66% Actual Mass % = (Response factor)(% of peak) Peak 1) 45.78/0.84 = 54.5 Peak 2) 28.56/0.99 = 28.8 Peak 3) 25.66/1.19 = 21.6 Theoretical ratio – 1:1:1 Actual ratio – 1:1:2

Discussion: The boiling point measurement is useful in indicating a substances purity as well as measuring the RI. If there are any inconstancies in the substances, we will be able to tell from the boiling point and refractive index. In D2 of the experiment, the measured boiling point was 71 C and we were able to identify the compound as Ethyl acetate with a percent error of 7.9%. In E1 of the experiment, we obtained the unknown #6 which was hexane with a measured boiling point of 24C. The percent error was as low as .116%. Conclusion: In this experiment, we were able to successfully identify two substances: ethyl acetate and hexane, by measuring their boiling points and refractive indexes. An important thing to remember when performing the lab is that some of these substances boil at a rather high temperature. Therefore, you may find it helpful to cover your boiling substance with aluminum foil in order to trap the heat. This will allow your substance to reach its boiling point more quickly. References: Schoffstall, A.; Gaddis B.; Drueling, M.; Melting Point; Microscale and Miniscale Organic Chemistry Laboratory Experiments, McGraw-Hill, (2011), 28-34 and 83 - 91. Mohrig, J.R.; Alberg, D.G.; Hofmeister, G.E.; Schatz, P.F.; Hammond, C.N.; Laboratory Techniques in Organic Chemistry; Freeman, New York, 2014, 174-176; 206-211; 291-308...