Lab 4
Fractional Distillation
Objective To separate a mixture of two liquids by collecting vapors at
their boiling point.
Experiment Pour about 50 mL of mixture into a grad. cyl.
Soak a paper strip in the mixture. Hold the paper
over the burner to test for flammability. Record
results
Time (min)
0
0.5
1.0
1.5
…
Heat mixture gradually and collect 2 fractions
Temp (°C)
Odor
Mixture
Fraction 1
Fraction 2
Fraction 3
(leftover in
flask)
Flammability
Analysis 1. Construct a graph of temperature vs. time for the heating of
the solution. Place the time along the horizontal and the
temperature along the vertical axis. Only include the temperature
range you recorded along the vertical for a more accurate graph.
Label the graph.
Results -
Questions 1. Why is this method of separation called “fractional” distillation?
2. What would the flat line in your graph indicate?
3. Propanol is an compound that has a boiling point around 98̊C.
Explain why a mixture of propanol and water would be difficult
to separate by fractional distillation.