Fractional Distillation of
Two Volatile Liquids
Containing Non-volatile
Impurities
Pour 60 mL of mixture into a 100 mL round-bottomed flask. Add your magnetic stirring bar.
Make note of the color and clarity of the
mixture on your lab data sheet.
Careful attention should be paid to the
positioning of the thermometer.
Have your instructor examine your apparatus
before commencing heating.
Place a 100 mL graduated cylinder so that the tip of the condenser is centered over
the neck of the cylinder, as shown on the demonstration set-up.
Place a 100 mL beaker directly under the suspended 100 mL graduated cylinder.
Wrap aluminum foil around the Still head and still pot.
Start the mixture stirring, heating initially at ”7”. Adjust heat so that the distillate comes over at
About 1-2 drops/second.
Collect
the first fraction in your 100 mL graduated cylinder when the thermometer
reaches a plateau. Record the
temperature every 2 mL thereafter.
When the drip rate slows to an occasional drop every so often, remove the 100 mL graduated cylinder,
allowing subsequent drops to fall into the 100 mL beaker. Continue collecting liquid in the beaker and noting temperature readings at 2 mL intervals until a second plateau is reached. When the thermometer reaches the second plateau, collect the second fraction, in your 50 mL graduated cylinder, recording the temperature every 2 mL.
Continue
distillation for 2or 3 more 2 mL increments, recording each temperature.
Record the volume of the
first, second and third fractions
collected, then, return them to the recovery bottles/flasks in the front of
the lab
Plot a
Temperature vs. Volume graph of your lab data on your lab report form.