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Petroleum is a naturally occurring, yellowish-black liquid found in geological formations beneath the Earth's surface, used as fuel and raw material in the chemical industry.
In many countries, the word used for "petroleum" is "petrol", which, in English-speaking countries is used for gasoline. This may sometimes lead to confusion.
Components of petroleum are separated using a technique called fractional distillation, i.e. separation of a liquid mixture into fractions differing in boiling point by means of distillation, typically using a fractionating column.
Petroleum contains a variety of chemical compounds, such as:
- Alkanes (paraffins): between 15 to 60%
- Naphthenes: between 30 to 60%
- Aromatics: between 3 to 30%
- Asphaltics: <10%
Petroleum is a black viscous liquid, with a strong characteristic odor. It is immiscible with water.
Petroleum is flammable.
Raw petroleum is not sold, due to safety reasons, and the fact that is does not store well. Its purified components however, are much more available.
Various methods of producing "bio-petroleum" have been developed over the years from biomass.
Handling and safety
Crude petroleum has benzene and other aromatics which are known to be carcinogenic.
Petroleum does not store well over long time, and should be used quickly.