5 - DISTILLATION

• WHAT IS DISTILLATION?

  separating a mixture of two liquids with different boiling points
• KEY POINTS OF SIMPLE DISTILLATION APPARATUS?

  • water bath/ electric heater to heat mixture
  • anti-bumping granules prevent large bubbles forming
  • bulb of thermometer must be pointing downwards
  • tilted condenser to allow liquid to reach collection flask
  • collection flask must not be sealed
• PURPOSE OF SIMPLE DISTILLATION?

  isolate a low boiling point product from a mixture
• PURPOSE OF FRACTIONAL DISTILATION?

  collect and separate all liquids in a mixture
• FRACTIONAL DISTILLATION?

  1. Fractionating column inserted between flask and condenser
  2. Flask heated until thermometer reads boiling point of most volatile component
  3. Column creates temperature gradient (hottest at top)
  4. Most volatile component remains a gas at top of column, collected through condenser
  5. Process repeated until all fractions obtained
• WHAT IS THE IMPORTANCE OF ANTI-BUMPING GRANULES?

  prevent mixture boiling over condenser creating undesired reagents/ impurities
• WHY MUST THE ENTIRE SYSTEM NOT BE AIR TIGHT?

  when system is heated, air expands and may cause apparatus to crack
• SIMPLE DISTILLATION?

  1. Heat mixture in round flask using water bath/ electric heater
  2. With a still head containing a thermometer
  3. Attached to a condenser with a ice cooled collecting vessel (to reduce evaporation of product)
  4. Collect sample at boiling point of product