Fractional Distillation Experiments
- Fractional distillation is chiefly used to purify liquids by removing impurities according to their volatility. The process involves heating a mixture until substances begin to vaporize one at a time, starting with those with the lowest boiling point. Vapors are condensed and collected in respective flasks. Fractional distillation differs from simple distillation because a fractionating column is used, which allows for a larger area in which a number of distillation cycles can occur. This improves the separation process.
- A simple fractional distillation experiment involves the separation of two organic liquids with boiling points that differ by more than 10 degrees Celsius, or 50 degrees Fahrenheit. Scientists commonly conduct this experiment in chemistry laboratories. In certain cases, the components of the mixture are unknown and are identified by determining the boiling point and refraction index of both liquids, which can be calculated via the distillation process. Scientists collect temperature and volume data from the distillate.
- There are a number of different substances in crude oil that vary in density, size and chemical structure. However, boiling point differences enable separation by fractional distillation. Workers heat crude oil to around 600 degrees Celsius, or 1,112 degrees Fahrenheit, using high-pressure steam. The fractionating column temperature decreases with an increase in height and contains a number of trays that collect vapor as it rises and condenses into liquid fractions. This allows the separation of components with the slightest differences in boiling points.
- There are experiments designed to mimic the industrial methods of crude oil refining via fractional distillation. A crude oil substitute is used: Real crude oil isn't permitted in school laboratories, as it contains carcinogenic compounds such as benzene. The substitute is still harmful and highly flammable and must be handled with caution. Apparatus is usually kept especially for this experiment: It becomes difficult to clean due to the nature of the crude oil alternative.
