Simple distillation
Distillation separates a volatile organic product from a reaction mixture. Heating produces vapour, the vapour enters a condenser and cooling changes it back into liquid for collection as the distillate.
- Use an electric heater or heating mantle when flammable organic liquids are heated.
- Add anti-bumping granules before heating so boiling is smoother and less violent.
- Position the thermometer bulb at the vapour take-off leading into the condenser.
- Cooling water enters through the lower condenser connection and leaves through the higher connection.
- The condenser slopes towards the receiving vessel.
- Do not seal heated apparatus containing volatile liquids because pressure could build up.
Collecting the required fraction
The thermometer measures the temperature of the vapour entering the condenser. When the boiling point of the required product is known, collect the distillate produced within about of that temperature.
Discard material that distils before the required temperature range and use a clean receiving vessel for the desired fraction. Stop collecting the product if the temperature rises above the upper limit of the range.
Exam Tip: In a distillation diagram, show the thermometer bulb at the vapour take-off into the condenser and cooling water entering at the lower condenser connection.