Fractional Distillation

Fractional Distillation is the process of distillation that is used to separate the components of a mixture of liquids or for purification of a liquid mixture or for selective recovery or purification of certain components from the mixture of two or more liquids.

In this process, the boiling points of these components are varied from one another and hence the components get separated from one another. It is a way of taking a liquid and separating out different compounds in that liquid. It’s useful in chemistry and biology, among other areas.  it is also used to make purer alcohol.

Even though you have a great liquor, you can further improve it by distilling it. That way you can make a better product with fewer resources.

It is a kind of distillation in which two or more liquids are separated. Typically, the technique comprises numerous distillations and condensations, and the mixture is separated into fraction components.

The separation process occurs primarily when the mixture evaporates at a given temperature range when separate components of the mixture cease to react with one another, allowing them to become essentially independent liquids.


This procedure requires only a few pieces of specialized equipment. A distillation flask, condenser, receiver, and column are required.

A thermometer is optional but required if you want to analyze the varied temperatures of both liquids separately in order to compute the experiment’s findings more precisely. The solution is added to the distilling flask and then the fractionating column is connected to the main distilling flask.

Fractional distillation procedure diagram

Heat is applied and it increases in a slow manner. The mixture starts boiling and vapor starts rising from the volatile component A. The vapors are then sent via the condenser, where they are converted back into a liquid and collected and stored in the receiver.

This continual vaporization and condensation procedure is performed until the two individual mixes are completely separated and no longer require treatment together.

Principle of Fractional Distillation

  • When any liquid mixture is heated, the one with the lower boiling point evaporates and converts to vapors.
  • The volatility of the mixture is determined by how quickly the liquid and gas phases are in equilibrium. The faster it happens, the more volatile is the mixture.
  • When the vapor is cooled, it condenses and the more volatile materials will form in a liquid state.
  • The process of vaporization followed by condensation is referred to as distillation (liquefaction). When this distillation process is repeated, a more volatile component in the liquid form will stay pure. Components of a liquid-liquid combination can be isolated as a pure material using the this process.

Various liquids boil and evaporate at different temperatures, which is the essential premise of this sort of distillation. As a result, when the combination is heated, the material with the lower boiling point converts into vapors first.


  • Water is purified by fractional distillation, while ethanol and water are separated using this method.
  • it is used in numerous sectors, including oil refineries and chemical facilities, to purify and separate various organic molecules.
  • Fractional distillation can also be used to separate (liquefied) air.
  • Components such as liquid nitrogen, oxygen, and concentrated argon are obtained.
  • Distillation is used to make high-purity silicon from chlorosilanes. Silicon is commonly used in semiconductors.

Simple vs. Fractional Distillation

The fractionating column naturally separates chemicals depending on their boiling points, which distinguishes fractional distillation from ordinary distillation.

Simple distillation may be used to isolate compounds, but it needs precise temperature control because only one “fraction” can be isolated at a time.

How do you know whether to separate a combination using basic distillation or fractional?

Simple distillation is faster, simpler, and consumes less energy, but it is only practical when the boiling points of the desired fractions differ significantly (more than 70 degrees Celcius). If the temperature difference between the fractions is minor, fractional distillation is your best option.

Industrial Distillation

Fractional distillation is a popular version of the distillation process used in several industries. While the idea behind this process remains the same (the separation process of liquids), it is carried out on a larger scale.

Mostly, large vertical cylindrical industrial towers are often known as “distillation columns” or “distillation or fractionation towers.”

These towers use reflux, which ensures the complete separation of mixtures and chemicals that have to be separated by quality control.

Fractional Distillation of Crude Oil

Fractional distillation is a distillation process of distilling mixtures by using its apparatus. it was first used by the alchemists of medieval times.

The process is based on the principle that different components in mixtures have different boiling points and therefore when heated, vaporization starts with the component with the lowest boiling point.

This process is used in the petroleum industry to obtain a large number of products from crude oil. The process of fractional distillation is also referred to as the process of distillation of a reactive distillation

Fractional Distillation of Petroleum

Fractional distillation is a distillation process that separates a complex mixture into fractions of different boiling points, using more than one distillation column. It is a process used to separate mixtures in which the different components have different boiling points.

For example, it is used in the distillation of crude oil into different fractions such as kerosene, gasoline, and petrochemicals.

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