Experiment 6:  Simple and Fractional Distillation

Experiment 6: Simple and Fractional Distillation PowerPoint PPT Presentation


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WWU -- Chemistry. Experiment 6: Simple and Fractional Distillation. Work in pairs. Each pair will conduct both the simple and fractional distillations. There are three unknowns, A, B, and C. Perform the experiment as follows:Day One: Working in pairs, use simple distillation to separate the unknown (Experiment 6A).Day Two: Again, working in pairs, repeat the experiment using fractional distillation on the same unknown (Experiment 6A)Do not do Experiment 6BThe products from each day's dis29822

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Experiment 6: Simple and Fractional Distillation

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1. WWU -- Chemistry Experiment 6: Simple and Fractional Distillation Reading Assignment Experiment 6 (pp. 51 -57) Technique 13, Parts A (pp. 694-702) Technique 14 (pp. 703-715) Technique 15 (pp. 715-732) Technique 22 (pp. 797-818)

2. WWU -- Chemistry Experiment 6: Simple and Fractional Distillation Work in pairs. Each pair will conduct both the simple and fractional distillations. There are three unknowns, A, B, and C. Perform the experiment as follows: Day One: Working in pairs, use simple distillation to separate the unknown (Experiment 6A). Day Two: Again, working in pairs, repeat the experiment using fractional distillation on the same unknown (Experiment 6A) Do not do Experiment 6B The products from each day’s distillation will be analyzed by gas chromatography.

3. WWU -- Chemistry Key Point! When conducting a distillation, the vapor should be richer in the lower boiling component than what you started with.

4. WWU -- Chemistry Simple Distillation: Apparatus

5. WWU -- Chemistry Correct Thermometer Placement

6. WWU -- Chemistry

7. WWU -- Chemistry Temperature Behavior During Distillation

8. WWU -- Chemistry Phase Diagram: Two Component Mixture of Liquids

9. WWU -- Chemistry

10. WWU -- Chemistry Vapor-Liquid Composition Curve (Benzene vs. Toluene)

11. WWU -- Chemistry

12. WWU -- Chemistry When will simple distillation do a reasonable job of separating a mixture?

13. WWU -- Chemistry Raoult’s Law

14. WWU -- Chemistry Raoult’s law calculations

15. WWU -- Chemistry Fractional Distillation: Apparatus

16. WWU -- Chemistry Vaporization-Condensation

17. WWU -- Chemistry Temperature vs. Volume: Fractional Distillation

18. WWU -- Chemistry Fractional Distillation Phase Diagram

19. WWU -- Chemistry How many theoretical plates are need to separate a mixture starting at L? Looks like about 5 plates are needed to separate the mixture on the previous slide! Count the “tie-lines” (horizontal lines) to come up with the 5 plates (labelled with arrows on the next slide)!

20. WWU -- Chemistry Fractional Distillation Phase Diagram. The arrows indicate a theoretical plate!

21. WWU -- Chemistry Theoretical Plates Required to Separate Mixtures based on BP

22. WWU -- Chemistry Microscale distillation: Hickman Head

23. WWU -- Chemistry Azeotrope Some mixtures of liquids, because of attractions or repulsions between the molecules, do not behave ideally These mixtures do not obey Raoult’s Law An azeotrope is a mixture with a fixed composition that cannot be altered by either simple or fractional distillation An azeotrope behaves as if it were a pure compound, and it distills from beginning to end at a constant temperature.

24. WWU -- Chemistry Types of Azeotropes There are two types of non-ideal behavior: Minimum-boiling-point Boiling point of the mixture is lower than the boiling point of either pure component Maximum-boiling-point Boiling point of the mixture is higher than the boiling point of either pure component

25. WWU -- Chemistry Maximum Boiling-Point Azeotrope

26. WWU -- Chemistry Observations with maximum boiling azeotrope

27. WWU -- Chemistry Minimum Boiling-Point Azeotrope

28. WWU -- Chemistry Observations with minimum boiling azeotrope

29. WWU -- Chemistry Dean-Stark Water Separator

30. WWU -- Chemistry The Gas Chromatograph

31. WWU -- Chemistry Gas Chromatography: Separation of a Mixture

32. WWU -- Chemistry Gas Chromatogram

33. WWU -- Chemistry Triangulation of a Peak

34. WWU -- Chemistry Sample Percentage Composition Calculation

35. WWU -- Chemistry Gas Chromatography: Results

36. WWU -- Chemistry Compounds in unknowns: boiling points. There will only be two components in each unknown

37. WWU -- Chemistry Gas Chromatography: Standards

38. WWU -- Chemistry

39. WWU -- Chemistry Preparing distillation samples for gas chromatography

40. WWU -- Chemistry How to identify the components in your unknown mixture Use the retention time information from your gas chromatograms to provide a positive identification of each of the components in the mixture. Don’t rely on the distillation plot to determine the composition of your mixture!

41. WWU -- Chemistry Retention Times and Response Factors

42. WWU -- Chemistry First Fraction: Cyclohexane/Toluene Chromatogram

43. WWU -- Chemistry Data: Cyclohexane/Toluene First Fraction

44. WWU -- Chemistry Calculation of percentages from the data for fraction 1

45. WWU -- Chemistry Second Fraction: Cyclohexane/Toluene Chromatogram

46. WWU -- Chemistry Data: Cyclohexane/Toluene Second Fraction

47. WWU -- Chemistry Calculation of percentages from the data for fraction 2

48. WWU -- Chemistry First Fraction: Hexane/Heptane Chromatogram

49. WWU -- Chemistry Data: Hexane/Heptane First Fraction

50. WWU -- Chemistry Calculation of percentages from the data for fraction 1

51. WWU -- Chemistry Second Fraction: Hexane/Heptane Chromatogram

52. WWU -- Chemistry Data: Hexane/Heptane Second Fraction

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