Oil

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For the fossil fuel, see Petroleum. For other uses, see Oil (disambiguation).

General structure of a triglyceride, the main constituent of vegetable oil and animal fats

Synthetic motor oil being poured

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 otherwise unrelated chemical structures, properties and uses, including vegetable oils, petrochemical oils, and volatile essential oils. All oils can be traced back to organic sources.

[edit] Types

[edit] Essential oil

An essential oil is a concentrated, hydrophobic liquid containing volatile aroma compounds from plants. An oil is 'essential' in the sense that it carries a distinctive scent, or essence, of the plant. Essential oils do not, as a group, need to have any specific chemical properties in common, beyond conveying characteristic fragrances. In history, oil has been used by Vikings, Spartans, etc. in war as they believed it made them stronger.^{[citation needed]}

Essential oils are generally extracted by distillation. Other processes include expression, or solvent extraction. They are used in perfumes, cosmetics and bath products, for flavoring food and drink, and for scenting incense and household cleaning products.

[edit] 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 its components, such as kerosene, paraffin waxes, gasoline, diesel 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, ranging from rocks, to underground traps, to 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 labelled as petrochemicals) have become such a crucial resource to human civilization in modern times they are often referred to by the ubiquitous term of "oil" itself.

[edit] Organic oils

Oils are 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, is lipids.

Lipids, ranging from waxes to steroids, are somewhat hard to characterize, 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.

[edit] Synthetic oils

Synthetic oil is a lubricant consisting of chemical compounds which are artificially made (synthesized) from compounds other than crude oil (petroleum). Synthetic oil is used as a substitute for lubricant refined from petroleum, because it generally provides superior mechanical and chemical properties than those found in traditional mineral oils.

[edit] Applications

A bottle of olive oil used in food.

[edit] Food

Many edible plant and animal oils and fats are used 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 some foods e.g. stir fry.

Health advantages are claimed for a number of specific oils such as omega 3 oils (fish oil, flaxseed oil, etc), evening primrose oil, and olive oil. Trans fats, often produced by hydrogenating vegetable oils, are known to be harmful to health.

[edit] 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 stabilised and grow faster.^{[citation needed]}

[edit] Fuel

Main article: Petroleum

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.

[edit] Electricity generation

Oil and any of its more refined products are often used to create electricity. This is done by means of a steam engine. The steam engine turns the thermal energy into rotary motion, which can then be transformed into electricity, by means of a generator.

[edit] Heat transport

Many oils have higher boiling points than water and are electrical insulators, making them useful for liquid cooling systems, especially where electricity is used.

[edit] 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.

[edit] Painting

Color pigments can be easily suspended in oil, making it suitable as supporting medium for paints. The slow drying process and miscibility of oil facilitates a realistic style. This method has been used since the 15th century.

[edit] Petrochemicals

Main article: 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.

[edit] Other uses

Sulfuric acid has been called oil of vitriol in pre-scientific times, due to its viscous consistency. Even in modern times, it is sometimes called vitriolic acid, and caustic personalities are called "vitriolic".^{[citation needed]} Sulfuric acid is not a petrochemical, and in modern parlance, is not an oil.^{[citation needed]}

[edit] Religion

Oils have been used throughout history as a fragrant or religious medium. Oil is often seen as a spiritually purifying agent. It is used in religious ceremonies, such as the chrism used in baptism, and has traditionally been used to anoint kings and queens. Oil that is associated with one or more saints is known as "oil of saints" and believed by some to have beneficial properties, as is "oil of martyrs"^[1].

[edit] See also

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

[edit] References

^ CATHOLIC ENCYCLOPEDIA: Oil of Saints

[edit] External links

Petroleum Online e-Learning resource from IHRDC

[0] CATHOLIC ENCYCLOPEDIA: Oil of Saints

[1]

Oil