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UCLA CHEM 20L - Distillation and GC Report Guidelines

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Chemistry 20LFall 2005Distillation and Gas Chromatography (GC) Report Guidelines(II) Pre-lab Assignment QuestionsDO NOT DRAW ANY SKETCHES ON YOUR ORIGINAL GC CHROMATOGRAMSChemistry 20L Fall 2005 Distillation and Gas Chromatography (GC) Report Guidelines Pre-lab Work (Individual) (I) On-line Technique Videos and Resources For This Experiment Click on the title below to download the video (requires Real Player) (1) Laboratory Safety (this video was shown on the first day of the lab) (2) Gas Chromatography (GC) (3) Simple Distillation If you have trouble downloading the videos, go to the following Web site and click on the appropriate title to download the video. http://oid.ucla.edu/Webcast/Chemistry/ (4) Basic Theory on Gas Chromatography (5) Simple Distillation (II) Pre-lab Assignment Questions Complete the questions on page 83-84. For question #2, you may also want to use the Online version of the Merck Index and the following Web site). http://chemfinder.cambridgesoft.com/ For question #3 refer to the online resource listed above for concepts in gas chromatography (GC). (III) Introductory Report material. Be sure to include • The title of the experiment and date. • A reference. Include any changes to the procedure that you know you will make. • A short introduction (Summarize in two or three sentences the goals of the experiment.) • A brief flow chart summary of the key procedures of the experiment • MSDS information for toluene and ethyl acetate. • A data table to record the specific temperatures and volumes of the three fractions that you will collect in the in the distillation and a second table to contain the instrument setting used on the GC. Post-lab Work: (This is a GROUP report. TURN IN ONLY ONE POST-LAB REPORT PER GROUP) Data and Observations: • Write the names of the group members on the report. Write down the responsibilities of each group member in writing this report as well as in performing the experiment. • Record the temperature at which the first drop of condensate forms and the temperature ranges over which each of your fractions distilled.• Keep a complete record of the boiling point ranges of the fractions you collect and the voles of each fraction. • Label each of your gas chromatograms as to the sample injected. Data Analysis: • Calculate the % composition of each of your fractions from the gas chromatograms. Show ALL your work. Make sure your group attaches the ORIGINAL GC chromatograms for the various fractions that you obtained in the lab to this post-lab report. • Compare the retention time of the standard toluene/ethyl acetate mixture with your samples. What can you conclude? Explain. Conclusion: • Summarize your results (again) • Justify the % composition results from the gas chromatograms. In other words, are they what you expected based on the theory of simple distillation? - Discuss how you could have achieved a better separation in the distillation. Application: • In your notebook, trace the GC chromatogram of your first distillate fraction • Based on the following conditions, sketch the chromatograms that you would have obtained if • there had been twice as much toluene in the fraction • the GC column had been twice as long • the temperature of the column had been higher • the chart paper advance had not been turned on. DO NOT DRAW ANY SKETCHES ON YOUR ORIGINAL GC


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UCLA CHEM 20L - Distillation and GC Report Guidelines

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