The Basics of Distillation
Distillation is a process used to separate the components of a liquid mixture by taking advantage of differences in their boiling points. It involves heating the mixture to the boiling point, then collecting and condensing the resulting vapor.
The component with the lowest boiling point vaporizes first. As the vapor rises and condenses, it can be collected separately from the original liquid mixture. This allows the components to be isolated from each other.
How a Simple Distillation Setup Works
A simple distillation setup consists of a flask, a condenser, and a collection vessel.
The liquid mixture is heated in the flask, either over a burner or with an electric heating mantle. As it boils, vapor rises up into the condenser. The condenser has cool water continually running through it, which causes the vapor to condense back into liquid form.
The condensate drips down into the collection vessel, separating it from the remaining mixture in the flask. Since the component with the lowest boiling point vaporizes first, it will condense and be collected first before the other components.
Fractional Distillation for More Precise Separation
Simple distillation works well for crude separations. But when components have boiling points close together, a more precise method called fractional distillation is used.
A fractional distillation setup uses a vertical column attached above the distillation flask. The column provides more surface area for vapor condensation and liquid re-evaporation.
As vapor rises up the column, it partially condenses and re-vaporizes multiple times. This allows better separation of components based on small differences in boiling point.
The condensed liquid fractions are collected separately from the side of the column at different heights. The component with the lowest boiling point condenses at the top of the column, with progressively higher boiling fractions condensing further down.
Applications of Distillation
Distillation has many uses:
- Purifying drinking water by removing salt and other impurities
- Separating mixtures in oil refining to produce gasoline, diesel, kerosene, etc.
- Extracting liquors like brandy, whiskey, vodka, etc. from fermented solutions
- Isolating natural products in a chemistry lab
- Desalinating seawater to produce fresh water
The next time you enjoy a refreshing glass of purified water or distilled spirit, you can appreciate the distillation process that helped create it!