Distillation

A diagram of a simple still, in which component A is the one being purified

Distillation is a process of separating components of a mixture whose boiling points differ. It is preformed by heating a mixture and condensing the resulting vapours. There are two major forms of distillation which are commonly used both industrially and in the laboratory, simple and fractional.

Some mixtures may be separated using simple distillation, if their boiling points are sufficiently different from each other. The classic example is that of water (bp 100°C) and ethanol (bp 78°C) which, although requiring multiple simple distillations to reach appreciable purity, can nonetheless be purified using simple distillation.

However, in some cases, simple distillation is not sufficient due to how similar the components boiling points are and fractional distillation becomes necessary, wherein an apparatus called a fractionating column is used to more precisely select for a single boiling point. A common example is that of acetone (bp 56°C) and methanol (bp 65°C), which is of great importance to anyone attempting to produce either of these compounds by the traditional wood gasification approach.

There are numerous applications of distillation, such as purifying and separating impurities in chemical compounds and cleansing water from bacteria, fungi and some viruses. Distillation was one of the major purification methods which lead to the development of modern chemistry and it remains integral.