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Chemistry LibreTexts

5.4: Vacuum Distillation

  • Page ID
    95711
  • Boiling commences when the vapor pressure of a liquid or solution equals the external or applied pressure (often the atmospheric pressure). Thus, if the applied pressure is reduced, the boiling point of the liquid decreases. This behavior occurs because a lower vapor pressure is necessary for boiling, which can be achieved at a lower temperature.

    • 5.4A: Overview of Vacuum Distillation
      Boiling commences when the vapor pressure of a liquid or solution equals the external or applied pressure (often atmospheric pressure). Thus, if the applied pressure is reduced, the boiling point of the liquid decreases. This behavior occurs because a lower vapor pressure is necessary for boiling, which can be achieved at a lower temperature.
    • 5.4B: Predicting the Boiling Temperature
      The boiling point of a liquid or solution drops when the pressure is reduced in a distillation apparatus. It is helpful to be able to predict the altered boiling point depending on the pressure inside the apparatus.
    • 5.4C: Step-by-Step Procedures for Vacuum Distillation
      A vacuum distillation apparatus can be constructed from a simple distillation setup although a fraction distillation can also be used. It is assumed that readers have previously performed a simple distillation under atmospheric pressure, so in this section are described differences between atmospheric and reduced pressure distillations.

    Contributors

    • Lisa Nichols (Butte Community College). Organic Chemistry Laboratory Techniques is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License. Complete text is available online.