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Fractional Distillation

A process, such as heating or boiling, used to separate volatile liquid solutions from each other into simpler/fractional substances. Such a process is carried out as components evaporate after being heated; upon reaching their boiling points, substances evaporate from the solution and are transferred to a new container through the process described below.


The process of Fractional Distillation in 5 Quick Steps

  1. Heat mixture containing 2 or more substances (e.g., water and ethanol solution).
  2. The mixture will begin to boil, vaporizing some substances (e.g., ethanol will start to boil at 78.4 °C (351.6 K) and water at 100 °C (212 °F)).
  3. Vapor goes through the fractional distillation column (long glass tube).
  4. Vapor rises to the top and begins to cool down on its way into the second column. Condensers in commercial processes are the mechanics that cool down the vapor.
  5. Condensation (vapor to liquid) phase takes place as the vapor is cooled to liquid and finally the substance is transferred into a container on the other end of the second distillation column.

Real life examples of distillation

  • Petroleum refineries use distillation to separate crude oil (see external link #3 video) (e.g., the Vallero refineries "towers" that can be seen from the freeway in Vallejo, California).
  • Distillation in nature of water into purified water.


  1. Petrucci, Harwood, Herring, Madura. General Chemistry: Principles & Modern Applications, Ninth Ed. Upper Saddle River, NJ: Pearson Education, Inc., 2007.


  • Rajdeep Kular (UCD)