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Chemistry Lab Procedures and Announcements

Nov 7, 2024

Lecture Notes: Chemistry Lab Announcements and Procedures

Announcements

  • Quiz Number Nine: Covers Experiment 11, with possible questions on gas chromatography.
  • Lab Completion: Finish Experiment 8 (Fractional Distillation) if incomplete; complete Experiment 11.
  • Experiment 10: Gas chromatography information will be discussed.
  • Pre-lab: Prepare for Experiment 11; ensure you include all parts like the flow diagram.
  • Experiment 7 Report: Due this week, worth 75 points.
  • Next Week: Quiz 10, Experiments 12 and 13 (Thin Layer Chromatography).
  • Due Dates:
    • Experiment 8 & 11 Report: November 19th (Tuesday Labs), November 21st (Thursday Labs).

Reminders

  • Safety: Wear safety glasses, dress appropriately, and bring calculators.
  • Cleanup:
    • Do not mix water with organic waste.
    • Magnesium sulfate is inorganic; do not dispose in organic waste.
  • Registration Issues: Contact registrar if issues arise with Chem 256 registrations.

Experiment 8: Fractional Distillation

  • Alcohol Boiling Points:
    • 3-Heptanol or 4-Heptanol: ~156°C.
    • 3-Octanol or 4-Octanol: Mid 170s°C.
  • Fraction Collection:
    • Low boiling fraction: 20°C below BP.
    • Second fraction: Up to BP range.
    • Third fraction: At BP range.
  • Data Collection:
    • Mass of product.
    • Prepare GC sample; ensure it's dry (no water/solids).
    • Add one drop to a GC vial, fill with pentane.
  • IR Spectrum: Compare to literature IR Spectrum.

Experiment 11: E1 Elimination Reaction

  • Process:
    • React alcohol with acid to form water, a leaving group.
    • Forms a carbocation leading to alkenes.
  • Possible Products:
    • 2-methyl-1-heptene or 2-methyl-2-heptene.
    • Carbocation rearrangement possible for more stable intermediates.
  • Sulfuric Acid Use:
    • Promotes elimination over substitution due to weak nucleophile.
  • Precautions:
    • Handle 9M sulfuric acid carefully.
    • Clean glassware with water post-experiment.
    • Cooling process for acid mixture.

Gas Chromatography (GC)

  • Chromatography Basics: Separation technique using inert gas.
  • Process:
    • Sample vaporized before entering column.
    • Separation based on boiling point, vapor pressure.
    • Detected using flame ionization detector (FID).
  • Sample Preparation:
    • Ensure sample is dry.
    • One drop into GC vial, fill with pentane.
  • Data Analysis:
    • Retention times indicate separation order.
    • GC tables for experiment reports.

Additional Notes

  • Waste Disposal:
    • Do not dispose of sulfuric acid in organic waste.
    • Use water to dilute and dispose.
  • Experiment Reports: Include IR and GC data.
  • Experiment 11 Safeguards: Be cautious with small organic layers; handle carefully to avoid loss.

This summary captures the key points discussed in today's chemistry lab session, focusing on upcoming quizzes, lab experiments, and proper lab procedures. Ensure to prepare adequately for the experiments and adhere to safety protocols.

Full transcript