![Italian olive oil 2007](https://upload.wikimedia.org/wikipedia/commons/e/e9/Italian_olive_oil_2007.jpg)
An oil is any
nonpolar chemical substance that is composed primarily of
hydrocarbons and is
hydrophobic (does not mix with
water) &
lipophilic (mixes with other oils). Oils are usually flammable and
surface active. 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,
vegetable, or
petrochemical in origin, and may be
volatile or non-volatile. They are used for food (e.g.,
olive oil
Olive oil is a liquid fat obtained from olives (the fruit of ''Olea europaea''; family Oleaceae), a traditional tree crop of the Mediterranean Basin, produced by pressing whole olives and extracting the oil. It is commonly used in cooking: f ...
), fuel (e.g.,
heating oil
Heating oil is any petroleum product or other oil used for heating; a fuel oil. Most commonly, it refers to low viscosity grades of fuel oil used for furnaces or boilers use for home heating and in other buildings. Home heating oil is often a ...
), medical purposes (e.g.,
mineral oil),
lubrication
Lubrication is the process or technique of using a lubricant to reduce friction and wear and tear in a contact between two surfaces. The study of lubrication is a discipline in the field of tribology.
Lubrication mechanisms such as fluid-lubric ...
(e.g.
motor oil
Motor oil, engine oil, or engine lubricant is any one of various substances used for the lubrication of internal combustion engines. They typically consist of base oils enhanced with various additives, particularly antiwear additives, deterg ...
), 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.
Etymology
First attested in English 1176, the word ''oil'' comes from
Old French ''oile'', from
Latin ''oleum'', which in turn comes from the
Greek (''elaion''), "olive oil, oil" and that from (''elaia''), "
olive
The olive, botanical name ''Olea europaea'', meaning 'European olive' in Latin, is a species of small tree or shrub in the family Oleaceae, found traditionally in the Mediterranean Basin. When in shrub form, it is known as ''Olea europaea'' ...
tree", "olive fruit". The earliest attested forms of the word are the
Mycenaean Greek , ''e-ra-wo'' and , ''e-rai-wo'', written in the
Linear B
Linear B was a syllabic script used for writing in Mycenaean Greek, the earliest attested form of Greek. The script predates the Greek alphabet by several centuries. The oldest Mycenaean writing dates to about 1400 BC. It is descended from ...
syllabic script.
Types
Organic oils
Organic oils are produced in remarkable diversity by plants, animals, and other organisms through natural
metabolic
Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cell ...
processes. ''
Lipid'' is the scientific term for the
fatty acids,
steroid
A steroid is a biologically active organic compound with four rings arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes that alter membrane fluidity; and a ...
s 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
proteins,
waxes (class of compounds with oil-like properties that are solid at common temperatures) and
alkaloids.
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
phospholipid
Phospholipids, are a class of lipids whose molecule has a hydrophilic "head" containing a phosphate group and two hydrophobic "tails" derived from fatty acids, joined by an alcohol residue (usually a glycerol molecule). Marine phospholipids typ ...
s 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.]
Mineral oils
Crude oil, or
petroleum, and its refined components, collectively termed ''
petrochemicals
Petrochemicals (sometimes abbreviated as petchems) are the chemical products obtained from petroleum by refining. Some chemical compounds made from petroleum are also obtained from other fossil fuels, such as coal or natural gas, or renewable sou ...
'', are crucial resources in the modern economy. Crude oil originates from ancient
fossilized organic materials, such as
zooplankton and
algae
Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...
, which
geochemical
Geochemistry is the science that uses the tools and principles of chemistry to explain the mechanisms behind major geological systems such as the Earth's crust and its oceans. The realm of geochemistry extends beyond the Earth, encompassing the e ...
processes convert into oil. The name "mineral oil" is a
misnomer
A misnomer is a name that is incorrectly or unsuitably applied. Misnomers often arise because something was named long before its correct nature was known, or because an earlier form of something has been replaced by a later form to which the name ...
, 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.
Applications
Cooking
Several edible vegetable and animal oils, and also
fats, 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 fry
Stir frying () is a cooking technique in which ingredients are fried in a small amount of very hot oil while being stirred or tossed in a wok. The technique originated in China and in recent centuries has spread into other parts of Asia and t ...
). Cooking oils are derived either from animal fat, as
butter,
lard
Lard is a semi-solid white fat product obtained by rendering the fatty tissue of a pig.[Lard]
entry in the o ...
and other types, or plant oils from
olive
The olive, botanical name ''Olea europaea'', meaning 'European olive' in Latin, is a species of small tree or shrub in the family Oleaceae, found traditionally in the Mediterranean Basin. When in shrub form, it is known as ''Olea europaea'' ...
,
maize,
sunflower
The common sunflower (''Helianthus annuus'') is a large annual forb of the genus ''Helianthus'' grown as a crop for its edible oily seeds. Apart from cooking oil production, it is also used as livestock forage (as a meal or a silage plant), as ...
and many other species.
Cosmetics
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
Hair conditioner is a hair care cosmetic product used to improve the feel, texture, appearance, and manageability of hair. Its main purpose is to reduce friction between strands of hair to allow smoother brushing or combing, which might otherwise ...
.
Religion
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 and
Christianity.
Painting
Color
pigments are easily
suspended in oil, making it suitable as a supporting medium for
paints. The oldest known extant oil paintings date from 650 AD.
Heat transfer
Oils are used as coolants in
oil cooling, for instance in electric
transformers. Heat transfer oils are used both as
coolants (see
oil cooling), for heating (e.g. in
oil heaters) and in other applications of heat transfer.
Lubrication
![Motor oil](https://upload.wikimedia.org/wikipedia/commons/b/bb/Mobil_1_motor_oil.jpg)
Given that they are non-polar, oils do not easily adhere to other substances. This makes them useful as
lubricants
A lubricant (sometimes shortened to lube) is a substance that helps to reduce friction between surfaces in mutual contact, which ultimately reduces the heat generated when the surfaces move. It may also have the function of transmitting forces, t ...
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 USA in 1980.
It is a long-running myth that
spermaceti
Spermaceti is a waxy substance found in the head cavities of the sperm whale (and, in smaller quantities, in the oils of other whales). Spermaceti is created in the spermaceti organ inside the whale's head. This organ may contain as much as of ...
from whales has still been used in NASA projects such as the
Hubble Space Telescope and the
Voyager
Voyager may refer to:
Computing and communications
* LG Voyager, a mobile phone model manufactured by LG Electronics
* NCR Voyager, a computer platform produced by NCR Corporation
* Voyager (computer worm), a computer worm affecting Oracle ...
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.
Fuel
Some oils
burn in liquid or
aerosol
An aerosol is a suspension (chemistry), suspension of fine solid particles or liquid Drop (liquid), droplets in air or another gas. Aerosols can be natural or Human impact on the environment, anthropogenic. Examples of natural aerosols are fog o ...
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
Petroleum, also known as crude oil, or simply oil, is a naturally occurring yellowish-black liquid mixture of mainly hydrocarbons, and is found in geological formations. The name ''petroleum'' covers both naturally occurring unprocessed crude ...
is pumped from the ground and is shipped via
oil tanker or a
pipeline
Pipeline may refer to:
Electronics, computers and computing
* Pipeline (computing), a chain of data-processing stages or a CPU optimization found on
** Instruction pipelining, a technique for implementing instruction-level parallelism within a s ...
to an
oil refinery. There, it is converted from crude oil to
diesel fuel (petrodiesel),
ethane (and other short-chain
alkanes),
fuel oil
Fuel oil is any of various fractions obtained from the distillation of petroleum (crude oil). Such oils include distillates (the lighter fractions) and residues (the heavier fractions). Fuel oils include heavy fuel oil, marine fuel oil (MFO), bun ...
s (heaviest of commercial fuels, used in ships/furnaces),
gasoline (petrol),
jet fuel
Jet fuel or aviation turbine fuel (ATF, also abbreviated avtur) is a type of aviation fuel designed for use in aircraft powered by gas-turbine engines. It is colorless to straw-colored in appearance. The most commonly used fuels for commercial a ...
,
kerosene,
benzene (historically), and
liquefied petroleum gas
Liquefied petroleum gas (LPG or LP gas) is a fuel gas which contains a flammable mixture of hydrocarbon gases, specifically propane, propylene, butylene, isobutane and n-butane.
LPG is used as a fuel gas in heating appliances, cooking e ...
. 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.
]
Chemical feedstock
Crude oil can be refined into a wide variety of component hydrocarbons. ''Petrochemicals
Petrochemicals (sometimes abbreviated as petchems) are the chemical products obtained from petroleum by refining. Some chemical compounds made from petroleum are also obtained from other fossil fuels, such as coal or natural gas, or renewable sou ...
'' are the refined components of crude oil
Circuit Component may refer to:
•Are devices that perform functions when they are connected in a circuit.
In engineering, science, and technology Generic systems
* System components, an entity with discrete structure, such as an assem ...
and the chemical products made from them. They are used as detergents, fertilizers, medicines, paints, plastics
Plastics are a wide range of synthetic polymers, synthetic or semi-synthetic materials that use polymers as a main ingredient. Their Plasticity (physics), plasticity makes it possible for plastics to be Injection moulding, moulded, Extrusion, e ...
, synthetic fiber
Synthetic fibers or synthetic fibres (in British English; see spelling differences) are fibers made by humans through chemical synthesis, as opposed to natural fibers that are directly derived from living organisms, such as plants (like cotton) ...
s, and synthetic rubber
A synthetic rubber is an artificial elastomer. They are polymers synthesized from petroleum byproducts. About 32-million metric tons of rubbers are produced annually in the United States, and of that amount two thirds are synthetic. Synthetic rubbe ...
.
Organic oils are another important chemical feedstock, especially in green chemistry.
See also
* Emulsifier
An emulsion is a mixture of two or more liquids that are normally immiscible (unmixable or unblendable) owing to liquid-liquid phase separation. Emulsions are part of a more general class of two-phase systems of matter called colloids. Altho ...
, a chemical which allows oil and water to mix
References
External links
*
Petroleum Online e-Learning resource from IHRDC
{{Authority control
Chemical substances