How to Troubleshoot a Distillation Column

Distillation is a procedure where an experimenter separates a mixture of liquids based on their tendency to vaporize. Generally, each liquid vaporizes at a different temperature. A distillation column is utilized during fractional distillation, where the difference in boiling points between the liquids in the mixture is less than 50 degrees C. The column is made of glass and usually filled with glass beads or metal shavings. The beads and metal shavings improve separation by increasing surface area.

Instructions

1. Attach the distillation column securely to the adjacent materials. The column should be placed between the distilling flask and the connecting adapter. If the column is not attached properly, the setup will fail to be a closed system. This will allow air to enter the column and compromise the results.

2. Dry the distillation column thoroughly. There should be no condensation on the inside column. This will contaminate the sample in the closed system and result in inaccurate results. In general, the distillation column should not be washed. It is extremely difficult to dry.

3. Lower the flame on the Bunsen burner. The mixture in the distilling flask must be heated at a constant and steady rate. It is better to heat at a low flame so that each liquid in the mixture can vaporize and separate fully. If the mixture is heated too quickly, the liquids will not have the opportunity to vaporize and recondense properly. The distillation column will not be able to adequately separate the liquids.

4. Lift the thermometer out of the distillation column. The thermometer is placed into the connecting adapter to gauge the boiling point temperature of the vaporized liquids. The thermometer bulb must be located at the opening of the connecting adapter where it connects to the condenser. If the bulb is dropped too low and enters the distilling column, the column will fail to produce pure samples of the separated liquids.

5. Place the distillation column vertically. Some people slightly slant the column in the setup. This would still separate the liquids, but would result in lower percent recovery and poorer separation of the liquids.

Tips & Warnings

• Cover the openings of the distillation column with a small amount of Vaseline. This will prevent the glass materials from sticking after distillation.

• Keep the distillation column in a clean area. It is very difficult to get any small pieces out of the column if it gets contaminated.

References

• Distillation Column Control
• Fractional Distillation