Page 25 - Curriculum Visions Dynamic Book

Thermometer
Distilling hydrocarbons in the laboratory
Crude oil is a mixture of a variety of components, each with a different boiling point. The easiest way to separate out the components is to heat the oil.
The principle of the process is shown in this laboratory glassware setup. The flask of oil
is heated, which, depending on the degree of heating, will vaporize a range of compounds.
As the vapours rise through the glassware,
the “lightest” fraction escapes from the top of the fractionating column and enters the condenser.
crude oil: a chemical mixture of petroleum liquids. Crude oil forms the raw material for an oil refinery.
fraction: a group of similar components of a mixture. In the petroleum industry the light fractions of crude oil are those with the smallest molecules, while the medium and heavy fractions have larger molecules.
petroleum: a natural mixture of a range of gases, liquids
and solids derived from the decomposed remains of plants and animals.
 Distillation apparatus for the laboratory. Condenser
 The fractions not distilled return to the distillation flask, passing down the fractionating column.
Water out
Fractionating column
Gases given off (which could be collected)
Distilling flask
Liquid to be distilled such as crude oil
Heat
Water in
Fraction collects in receiver flask
Laboratory vs industrial methods
A laboratory apparatus can only
distil chemicals in batches. Thus, for example, the equipment shown here
is heated to a certain temperature
so that it will distil just one of the fractions. The temperature of the liquid is then adjusted and another fraction is obtained. By contrast, industry has to produce its products continuously using equipment such as that shown on the next page.
Chemical industries strive to keep precise control over temperatures so that they can extract a wide range of products at the same time.
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