An oil is any nonpolar chemical substance that is composed primarily of and is hydrophobe (does not mix with water) and lipophilicity (mixes with other oils). Oils are usually flammable and surfactant. Most oils are unsaturated lipids that are liquid at room temperature.
The general definition of oil includes classes of chemical compounds that may be otherwise unrelated in structure, properties, and uses. Oils may be animal fats, vegetable oil, or petrochemical in origin, and may be volatile or non-volatile.
They are used for food (e.g., olive oil), fuel (e.g., heating oil), medical purposes (e.g., mineral oil), lubrication (e.g. motor oil), and the manufacture of many types of paints, plastics, and other materials. Specially prepared oils are used in some religious ceremonies and rituals as purifying agents.
First attested in English 1176, the word oil
comes from Old French oile
, from Latin oleum
which in turn comes from the Greek language
ἔλαιον ( elaion
), "olive oil, oil"
and that from ἐλαία ( elaia
tree", "olive fruit".
The earliest attested forms of the word are the Mycenaean Greek
and 𐀁𐁉𐀺, e-rai-wo
, written in the Linear B
Organic oils are produced in remarkable diversity by plants, animals, and other organisms through natural metabolic
is the scientific term for the
and similar chemicals often found in the oils produced by living things, while oil refers to an overall mixture of chemicals. Organic oils may also contain chemicals other than lipids, including
(class of compounds with oil-like properties that are solid at common temperatures) and
Lipids can be classified by the way that they are made by an organism, their chemical structure and their limited solubility in water compared to oils. They have a high carbon and hydrogen content and are considerably lacking in oxygen compared to other organic compounds and minerals; they tend to be relatively nonpolar molecules, but may include both polar and nonpolar regions as in the case of and steroids.
[Alberts, Bruce; Johnson, Alexander; Lewis, Julian; Raff, Martin; Roberts, Keith; Walter, Peter. Molecular Biology of the Cell. New York: Garland Science, 2002, pp. 62, 118-119.]
Crude oil, or petroleum
, and its refined components, collectively termed petrochemicals
, are crucial resources in the modern economy. Crude oil originates from ancient fossilized
, such as zooplankton
, which geochemical
processes convert into oil.
The name "mineral oil" is a misnomer
, in that minerals are not the source of the oil—ancient plants and animals are. Mineral oil is organic. However, it is classified as "mineral oil" instead of as "organic oil" because its organic origin is remote (and was unknown at the time of its discovery), and because it is obtained in the vicinity of rocks, underground traps, and sands. Mineral oil
also refers to several specific distillates of crude oil.
Several edible vegetable and animal oils, and also
, are used for various purposes in cooking and food preparation. In particular, many foods are fried in oil much hotter than boiling water. Oils are also used for flavoring and for modifying the texture of foods (e.g. stir frying
). Cooking oils are derived either from animal fat, as butter
and other types, or plant oils from olive oil
, corn oil
, sunflower oil
and many other species.
Oils are applied to hair to give it a lustrous look, to prevent tangles and roughness and to stabilize the hair to promote growth. See hair conditioner
Oil has been used throughout history as a religious medium. It is often considered a spiritually purifying agent and is used for anointing
purposes. As a particular example, holy anointing oil has been an important ritual liquid for Judaism
Oils have been consumed since ancient times. Oils hold lots of fats and medical properties. A good example is olive oil. Olive oil holds a lot of fats within it which is why it was also used in lighting in ancient Greece and Rome. So people would use it to bulk out food so they would have more energy to burn through the day. Olive oil was also used to clean the body in this time as it would trap the moisture in the skin while pulling the grime to the surface. It was used as an ancient form of unsophisticated soap. It was applied on the skin then scrubbed off with a wooden stick pulling off the excess grime and creating a layer where new grime could form but be easily washed off in the water as oil is hydrophobic.
Fish oils hold the omega-3 fatty acid. This fatty acid helps with inflammation and reduces fat in the bloodstream.
are easily suspended in oil, making it suitable as a supporting medium for Oil paint
. The oldest known extant oil paintings date from 650 AD.
[ "Oldest Oil Paintings Found in Afghanistan", Rosella Lorenzi, Discovery News. February 19, 2008. ]
Oils are used as coolants in oil cooling
, for instance in electric transformers. Heat transfer oils are used both as
(see oil cooling
), for heating (e.g. in
) and in other applications of heat transfer.
Given that they are non-polar, oils do not easily adhere to other substances. This makes them useful as lubricants
for various engineering purposes. Mineral oils are more commonly used as machine lubricants than biological oils are. Whale oil
is preferred for lubricating clocks, because it does not evaporate, leaving dust, although its use was banned in the US in 1980.
It is a long-running myth that spermaceti from whales has still been used in NASA projects such as the Hubble Space Telescope and the Voyager program probe because of its extremely low freezing temperature. Spermaceti is not actually an oil, but a mixture mostly of wax esters, and there is no evidence that NASA has used whale oil.
Some oils Combustion
in liquid or aerosol
form, generating light
, and heat
which can be used directly or converted into other forms of energy such as electricity or mechanical work. In order to obtain many fuel oils, crude oil
is pumped from the ground and is shipped via oil tanker
or a pipeline to an oil refinery
. There, it is converted from crude oil to diesel fuel
(and other short-chain alkanes
(heaviest of commercial fuels, used in ships/furnaces), gasoline
(petrol), jet fuel
(historically), and liquefied petroleum gas. A barrel of crude oil produces approximately of diesel, of jet fuel, of gasoline, of other products, split between heavy fuel oil and liquified petroleum gases,
[ U.S. Energy Information Administration (EIA) — Retrieved 2011-10-02.]
and of heating oil. The total production of a barrel of crude into various products results in an increase to .
In the 18th and 19th centuries, whale oil was commonly used for lamps, which was replaced with natural gas and then electricity.
Crude oil can be refined into a wide variety of component hydrocarbons. Petrochemicals are the refined components of crude oil
and the chemical products made from them. They are used as detergents, fertilizers, medicines, paints, plastics, , and synthetic rubber.
Organic oils are another important chemical feedstock, especially in green chemistry.
Emulsifier, a chemical which allows oil and water to mix