What is "fractional distillation"

Fractional \Frac"tion*al\, a.

1. Of or pertaining to fractions or a fraction; constituting a fraction; as, fractional numbers.

2. Relatively small; inconsiderable; insignificant; as, a fractional part of the population.

   Fractional crystallization (Chem.), a process of gradual and approximate purification and separation, by means of repeated solution and crystallization therefrom.

   Fractional currency, small coin, or paper notes, in circulation, of less value than the monetary unit.

   Fractional distillation (Chem.), a process of distillation so conducted that a mixture of liquids, differing considerably from each other in their boiling points, can be separated into its constituents.

Distillation \Dis`til*la"tion\ (d[i^]s`t[i^]l*l[=a]"sh[u^]n), n.

1. The act of falling in drops, or the act of pouring out in drops.

2. That which falls in drops. [R.]
   --Johnson

3. (Chem.) The separation of the volatile parts of a substance from the more fixed; specifically, the operation of driving off gas or vapor from volatile liquids or solids, by heat in a retort or still, and the condensation of the products as far as possible by a cool receiver, alembic, or condenser; rectification; vaporization; condensation; as, the distillation of illuminating gas and coal, of alcohol from sour mash, or of boric acid in steam.

   Note: The evaporation of water, its condensation into clouds, and its precipitation as rain, dew, frost, snow, or hail, is an illustration of natural distillation.

4. The substance extracted by distilling.
   --Shak.

   Destructive distillation (Chem.), the distillation, especially of complex solid substances, so that the ultimate constituents are separated or evolved in new compounds, -- usually requiring a high degree of heat; as, the destructive distillation of soft coal or of wood.

   Dry distillation, the distillation of substances by themselves, or without the addition of water or of other volatile solvent; as, the dry distillation of citric acid.

   Fractional distillation. (Chem.) See under Fractional.

n. A method of separating a mixture of liquids that have different boiling points

n. fractionation of a liquid by distillation

Fractional distillation is the separation of a mixture into its component parts, or fractions, separating chemical compounds by their boiling point by heating them to a temperature at which one or more fractions of the compound will vaporize. It uses distillation to fractionate. Generally the component parts have boiling points that differ by less than 25 °C from each other under a pressure of one atmosphere. If the difference in boiling points is greater than 25 °C, a simple distillation is typically used.