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JoVE Lab Manual
Lab: Chemistry
Education
Steam Distillation
 

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Learning Objectives

At the end of this lab, students should know...

What is the vapor pressure of a substance?

The vapor pressure of a pure substance is the pressure exerted by the gaseous phase on the liquid or solid phase in a closed container.

At what point does a liquid boil?

A liquid boils when the vapor pressure of the liquid is equal to the atmospheric pressure.

What is the difference between a miscible and immiscible solution?

A miscible solution contains substances that can form a homogeneous solution, whereas an immiscible mixture is composed of substances that cannot be mixed, and therefore form a heterogeneous mixture.

How is the total pressure of an immiscible mixture defined

In an immiscible mixture, the sum of the individual pure component vapor pressures equals the total vapor pressure of the solution.

How does the steam distillation setup differ from a simple distillation setup?

The steam distillation setup has a water reservoir, which lowers the boiling point of the mixture by forming an immiscible mixture with the organic compounds.

List of Materials

  • Lab stand (+2 for reference setup)
    10
  • Stirring hotplate (+1 for reference setup)
    5
  • Heating mantle (+1 for reference setup)
    5
  • Temperature controller (+1 for reference setup)
    5
  • 500-mL round-bottom flask with cork stand (+1 for reference setup)
    5
  • Distilling head (+1 for reference setup)
    5
  • Condenser (+1 for reference setup)
    5
  • Connecting tube (+1 for reference setup)
    5
  • 125-mL separatory funnel with glass stopper (+1 for reference setup)
    5
  • Claisen adapter (+1 for reference setup)
    5
  • Thermometer adapter (+1 for reference setup)
    5
  • Thermometer (+1 for reference setup)
    5
  • Small spatula
    5
  • Stir bar
    5
  • Joint clips (+4 for reference setup)
    20
  • Rubber tubing (+2 for reference setup)
    10
  • Vacuum grease
    5 tubes
  • Medium 3-prong clamp (+2 for reference setup)
    10
  • Ring support (+1 for reference setup)
    5
  • Conical funnel
    5
  • 250-mL round-bottom flask with cork stand (+1 for reference setup)
    5
  • 100-mL graduated cylinder
    5
  • 250-mL glass beaker
    10
  • 125-mL Erlenmeyer flask
    5
  • 500-mL glass beaker
    5
  • Filter paper
    5
  • Watch glass
    5
  • Diethyl ether
    300 mL
  • Anhydrous magnesium sulfate
    15 mg
  • Medium orange
    5
  • 10-mL graduated cylinder
    1
  • Blender
    1
  • Deionized water
    Dependent on lab size
  • Analytical balance (at least 1)
    Dependent on lab size

Lab Prep

Source: Lara Al Hariri at the University of Massachusetts Amherst, MA, USA

  1. Preparation of the Laboratory

    Here, we show the laboratory preparation for 10 students working in pairs, with some excess. Please adjust quantities as needed.

    • To begin, put on the appropriate personal protective equipment, including a lab coat, safety goggles, and gloves.
    • Set out the following glassware and equipment that the students will need to build the distillation apparatus (we suggest that students work in pairs):
       2    Lab stands
       1    Stir plate
       1    Heating mantle
       1    Temperature controller
       1    500-mL round-bottom flask with cork stand
       1    Distilling head
       1    Condenser
       1    Connecting tube
       1    Separatory funnel
       1    Claisen adapter
       1    Thermometer adapter
       1    Thermometer
       1    Small spatula
       1    Stir bar
       4    Joint clips
       2    Pieces of rubber tubing
       1    Tube of vacuum grease
       2    Standard clamps
       1    Ring support
       1    Conical funnel
       1    250-mL round-bottom flask and cork stand
       1    100-mL graduated cylinder
       2    150-mL beakers
       1    125-mL Erlenmeyer flask
       1    Filter paper
       1    500-mL beaker
    • You will need one blender to share between all of the groups. Place it in a central location along with a 10-mL graduated cylinder and a bottle of deionized water.
    • Next, assemble the steam distillation apparatus for the students to refer to during the experiment. First, place the two stands next to each other in the hood.
    • Then, put the stir plate on the base of one of the stands. Set the heating mantle on top of the stir plate and plug it into the temperature controller.
    • Clamp the 500-mL round-bottom flask to the stand above the heating mantle.
    • Locate the Claisen adapter and connect it to the flask.
    • Clamp the condenser to the second stand, orienting it so that it is nearly horizontal.
    • Connect the thermometer adapter to the distilling head and gently insert the thermometer until the bulb is in line with the side arm of the distilling head.
    • Then, add the distilling head into the outer arm of the Claisen adapter and connect the condenser to the distilling head.
    • Attach one piece of rubber tubing to the inlet of the condenser, which is the port furthest away from the distilling head.
    • Attach the other end of the tubing to the tap water faucet in the hood. Connect the second piece of rubber tubing to the other port, which is the outlet, and place the end of the tubing in the drain.
    • Now, get the separatory funnel and make sure that the stopcock is closed. Insert the separatory funnel into the Claisen adapter.
    • Finally, attach the connecting joint to the end of the condenser and attach a 250-mL round-bottom flask to the connecting joint. Secure each joint with a plastic clip.
    • Now that you have set up the demo apparatus, prepare the oranges. Each group will need 3 long peels on a watch glass, so obtain as many oranges and watch glasses as needed.
    • Peel all of the oranges and place 3 peels on each watch glass. Allow the peels to dry for two hours.
    • Next, obtain a bottle of magnesium sulfate and ensure that there is enough for each lab group to have a small spatula full, or about 2 mg each.
    • You will also need a bottle of diethyl ether. Each group will need 40 mL, so ensure that there is enough for the class size.
    • Finally, make sure there is a dedicated container for non-halogenated waste.

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