What Is Fractional Distillation and What Is It Used For?

In GCSE chemistry, there are many processes and experiments to teach in order to meet the curriculum. One of these is a process called fractional distillation, which students need to understand and explain thoroughly. Distillation experiments are done using a Bunsen burner, so make sure you know what this equipment is and how to use it, before learning about distillation.

In this article, our science team are exploring the fractional distillation definition and what you need to know at a GCSE level.

What Is Fractional Distillation?

Fractional distillation is a type of process which separates components in a chemical mixture into different fractions, or parts. They are separated by boiling point, and it is a process that is commonly used to purify chemicals. When conducting a distillation experiment, the vapour from a boiling solution passes through a tall column, known as a fractionating column.

The fractionating column is usually made of glass or plastic beads which work to improve the separation of the mixture because of the increased surface area. This surface area causes more condensation and evaporation. Along the length of the fractional distillation tower, the temperature gradually decreases. This causes the components with the highest boiling points to condense and return back to the solution, while those with a low boiling point will pass through the tower and collect near the top.

What Is Fractional Distillation Used For?

The process of fractional distillation is used for many everyday applications, and many substances and items we come across on a regular basis are a product of this process. Some common uses of fractional distillation are:

Crude Oil

Crude oil fractionation is probably the most widely used example of this process. Fuel oil, or petroleum, is primarily made up of hydrocarbons and it is a mixture of somewhere between 5 and 40 different carbon atoms. These components in crude oil are very useful, but only when they are separated out. Fractional distillation columns are often used in oil refineries as a way of separating oil into fractions such as diesel, gasoline, and kerosene.

Water

This distillation process is commonly used to purify water. With fractional distillation, and other substances mixed in with water can be easily separated and removed.

Silicon

Some industries, such as the electronics industry, rely heavily on fractional distillation being used to derive purified and concentrated silicon from chlorosilanes. This process is much easier and cheaper than traditional ways of manufacturing silicon.

Gases

Fractional distillation of air can be used to extract gases such as argon, nitrogen, and oxygen. The air is cooled to around -200 degrees Celsius so it turns to liquid form, and then fractionally distilled to separate the different gases.

What Is the Difference Between Simple Distillation And Fractional Distillation?

Many students confuse fractional distillation with simple distillation, and it is important that the differences are understood at a GCSE level. Simple distillation can only be used to isolate one type of chemical at a time, and only works with pure liquids that both have vastly different boiling points. Fractional methods can isolate components in more complex mixtures and those with close boiling points. Simple distillation is a simpler and faster method, but it does not suit all applications.

How To Demonstrate Fractional Distillation for GCSE Chemistry Classes?

A fractional distillation experiment is a common Bunsen burner experiment and great for demonstrating the process to a GCSE class. With the right lab equipment, you can show a class how petrol can be separated using fractional distillation methods. To do this experiment you will need:

• Round bottom flask
• Fractionating column
• Thermometer pocket
• Liebig Condensor
• Reduction adaptor
• Receiver adaptor
• Crude oil substitute
• Bunsen burner
• Tripod
• Gauze
• Rubber tubing

Begin by putting the crude oil substitute into the round bottom flask and attaching the fractional distillation column and the condenser. Slowly heat up the flask using the Bunsen burner and watch as the different hydrocarbons separate as they reach their different boiling points. At each temperature in the fractional distillation tower, different substances in the mixture will evaporate.

Begin with the burner at a low temperature and collect the liquid that has distilled into the beaker. Raise the temperature slightly to collect the next fraction from the liquid.

At EduLab, we have everything you need to demonstrate and set up your fractional distillation apparatus at GCSE level. For more information, contact our expert team today.