Introduction to Distillation

Distillation is a physical process used to separate mixtures that contain at least one liquid.

Process

Distillation involves heating a mixture until the liquid boils, capturing the resulting vapors, cooling the vapors until they condense, and collecting the condensed liquid.

Simple vs. Fractional Distillation

Simple distillation involves the collection of a single liquid from a mixture, whereas fractional distillation collects two or more different liquids. Fractional distillation is possible because all liquids have a unique boiling point. As a mixture is heated, the temperature rises until the temperature of the liquid with the lowest boiling point is reached. That liquid turns into vapor while the other components remain in their original liquid or solid form. Only after the first liquid boils completely off does the temperature begin increasing until the next boiling point is reached.

History

Ancient Arab chemists probably first used distillation around 3500 BC to make perfumes. Aristotle (384-322 BC) discussed distillation as a way to purify water, while Pliny the Elder (23-79 AD) made one of the earliest references to a still, the device used for distillation.

Scientific Uses

Distillation is used in chemistry to identify and purify organic compounds. Determining the boiling point of a compound through distillation identifies the compound since most organic materials have unique, well-known boiling points. Distillation is used to purify a compound by separating it from other materials with different boiling points.

Commercial Uses

Distillation has many commercial uses, including the production of gasoline, distilled water, alcohol, paraffin, and kerosene. Water purification and production of certain alcoholic beverages use simple fermentation while petroleum refineries use fractional distillation to produce products such as gasoline, diesel fuel, and kerosene.

References

• Distillation
• Fractional Distillation