Cambridge Encyclopedia :: Cambridge Encyclopedia Vol. 55

oil (botany) - Types, Examples, Applications

A fluid secreted by special glands in many plants, often forming food reserves in fruits and seeds such as olives, palms, rape, and flax. Volatile essential oils are produced by aromatic plants, especially in dry regions, and may help reduce transpiration or provide protection against animals. Edible oils are obtained from many plants, including soy beans, maize, olives, sunflowers, coconut, and rapeseed.

Emulsifiers allow oils and water to mix.

Types

Hydrocarbons

Certain oils are liquid hydrocarbons or mixtures thereof.

Triglycerides

The word oil also refers to triglycerides which are liquids at room temperature, usually in the context of cooking oil. The triglycerides in cooking oil tend to contain unsaturated fatty acid chains, hence the terms monounsaturate and polyunsaturate. This effect limits the degree of intermolecular attraction and so allows individual molecules to rotate with respect to each other, the condition for a daniel

Examples

Biological

Vegetable oil, non-violet oils extracted from plants, usually the seeds Essential oil, volatile aromatic oils extracted from plants Animal fat, obtained from animal sources

Mineral

Petroleum or "crude oil", a natural resource found in liquid state in the Earth's crust. Mineral oil, a by-product of the distillation of petroleum Oil shale, a group of sedimentary rocks which may be distilled to obtain petroleum Coal oil, distilled from bituminous shale or mineral wax

Synthetic

Synthetic oil, manufactured from smaller molecules using chemical processes

Applications

Cooking oil

Edible vegetable and animal oils are frequently used in cooking, due to their ability to reach higher temperatures than water.

Fuel oil

Oils contain a large amount of stored energy, which can be converted by burning into other forms of energy. Oils used for this purpose are usually derived from petroleum, but biological sources of energy are being evaluated as an alternative to the increasingly expensive crude oil. Suitable oils are often found in the mineral spectrum, as biological oils degrade quickly in most environmental conditions.

Petrochemistry

Petrochemistry is the process of refining crude oil into useful raw materials, plastics, and other oils.

Heat transport

Many oils have higher boiling points than water and lower electrical conductivity, allowing them to be used for liquid cooling systems, especially where electricity is used.

Painting

Color pigments can be easily suspended in oil, making it suitable as supporting medium for paints.

Religion

Oils have been used throughout history as a fragrant or religious medium.

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