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An oil is any substance that is liquid at ambient temperatures and is hydrophobic but soluble in organic solvents. Oils have a high carbon and hydrogen content and are nonpolar substances. The general definition above includes compound classes with, and uses, including vegetable oils, petrochemical oils, and volatile essential oils. All oils can be traced back to organic sources.

Etymology

First attested in English 1176, the word oil comes from Old French "oile", from Latin "oleum", which in turn comes from the Greek "ἔλαιον" (elaion), "olive oil, oil" and that from "ἐλαία" (elaia), "olive tree". The earliest attested form of the word is the Mycenaean Greek e-ra-wo, written in Linear B syllabic script.

Types

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Organic oils

Organic oil is also produced by plants, animals, and other organisms through organic processes, and these oils are remarkable in their diversity. Oil is a somewhat vague term in chemistry; instead, the scientific term for oils, fats, waxes, cholesterol, and other oily substances found in living things and their secretions, are lipids.

Lipids, ranging from waxes to steroids, are somewhat hard to characterise, and are united in a group almost solely based on the fact that they all repel, or refuse to dissolve in, water, and are however comfortably miscible in other liquid lipids. They also have a high carbon and hydrogen content, and are considerably lacking in oxygen compared to other organic compounds and minerals.

Mineral oil

Mineral oils, found in porous rocks underground, originated from organic material, such as dead plankton, accumulated on the seafloor in geologically ancient times. Through various geochemical processes this material was converted to mineral oil, or petroleum, and such. These are classified as mineral oils because they do not have an organic origin on human timescales, and are instead derived from underground geologic locations such as in rocks, underground traps, or sands.

Other oily substances can also be found in the environment; the most well-known of those is asphalt, occurring naturally underground or, where there are leaks, in tar pits.

Petroleum and other mineral oils (specifically labeled as petrochemicals) have become crucial resources to human civilization. In modern times, they are often referred to by the term of "oil" itself.

Applications

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Hair

Oil is used on hair to give it a lustrous look. It helps to avoid tangles and roughness to the hair. It also helps the hair to be stabilized and grow faster. See Hair conditioner. Anointing one's head with oil is a ritualistic practice in many countries.

Cooling

Oil is also used as coolant in various applications such as electric transformers.

Fuel

Almost all oils burn in aerosol form generating heat, which can be used directly, or converted into other forms of fuels by various means. The oil that is pumped from the ground is then shipped via oil tanker to an oil refinery. There, it is converted from crude oil to diesel fuel (petrodiesel), ethane (and other short-chain alkanes), fuel oils (heaviest of commercial fuels, used in ships/furnaces), gasoline (petrol), jet fuel, kerosene, and liquefied petroleum gas.

Electricity generation

Oil and any of its more refined products have been used to create electricity. This can be done by means of a steam engine, or by means of a turbine driven by exhaust gases. A steam engine turns the thermal energy into rotary motion, which can then be transformed into electricity, by means of a generator. In an exhaust gas turbine, the combustion products from burning the fuel expand, thereby turning a turbine. The turbine is coupled to an electric generator.

Lubrication

Due to their non-polarity, oils do not easily adhere to other substances. This makes oils useful as lubricants for various engineering purposes. Mineral oils are more suitable than biological oils, which degrade rapidly in most environmental conditions due to oxidation.

Painting

Color pigments can be easily suspended in oil, making it suitable as a supporting medium for paints. The slow drying process and miscibility of oil facilitates a realistic style. This method has been used since the 13th century.

Petrochemicals

Crude oil can be processed into petroleum; "petrochemicals" are chemical products made from raw materials of petroleum or other hydrocarbon origin. They are used in products such as detergents, fertilizers, medicines, paints, plastics, synthetic fibres, and synthetic rubber.

See also

• Emulsifier, allow oils and water to mix
• Lubrication
• Wax, compounds with oil-like properties that are solid at common temperature

References

This article includes a list of general references, but it lacks sufficient corresponding inline citations. Please help to improve this article by introducing more precise citations. (October 2009) (Learn how and when to remove this message)

1. oleum, Charlton T. Lewis, Charles Short, A Latin Dictionary, on Perseus Digital Library
2. ἔλαιον, Henry George Liddell, Robert Scott, A Greek-English Lexicon, on Perseus Digital Library
3. ἐλαία, Henry George Liddell, Robert Scott, A Greek-English Lexicon, on Perseus Digital Library
4. Palaeolexicon, Word study tool of ancient languages
5. Aftab, Hussain. "Composition of fatty acid". Physicochemical studies on sheep fat. VDM Verlag. Retrieved 26 May 2011.

External links

• Petroleum Online e-Learning resource from IHRDC

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• Oils
• Greek loanwords