Paraffin

From Free net encyclopedia

Paraffin is a common name for a group of high molecular weight alkane hydrocarbons with the general formula C_nH_2n+2, where n is greater than about 20, discovered by Carl Reichenbach.
In the UK, as well as in most Commonwealth countries, the fuel known in the U.S. as kerosene is called paraffin oil (or just paraffin), and the solid forms of paraffin are called paraffin wax.
Paraffin is also a technical name for an alkane in general, but in most cases it refers specifically to a linear, or normal alkane, while branched, or isoalkanes are also called isoparaffins. Compare olefin. (Latin parum (= barely) + affinis with the meaning here of "lacking affinity", or "lacking reactivity")

1 Physical and chemical properties
2 Liquid paraffin
3 Uses
4 See also
5 References

Physical and chemical properties

It is mostly found as a white, odourless, tasteless, waxy solid, with a typical melting point between about 47°C and 65°C. It is insoluble in water, but soluble in ether, benzene, and certain esters. Paraffin is unaffected by most common chemical reagents, but burns readily.

Pure paraffin is an extremely good electrical insulator, with a electrical resistance of <math>10^{17}</math> ohm meter. This is better then nearly all other materials except some plastics (notably teflon).

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Liquid paraffin

Liquid paraffin has a number of names, including nujol, mineral spirits, adepsine oil, alboline, glymol, liquid paraffin, paraffin oil, saxol, or USP mineral oil. It is often used in infrared spectroscopy, as it has a relatively uncomplicated IR spectrum. When the sample to be tested is made into a mull (a very thick solution), liquid paraffin is added so it can be spread on the disks to be tested.

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Uses

Candlemaking
Coatings for waxed paper or cloth.
Coating for many kinds of hard cheese, like Edam cheese.
As anticaking-, moisture repellent- and dustbinding coatings for fertilizers.
Preparing specimens for histology.
Solid propellant for hybrid rockets
Sealing jars, cans, and bottles
In dermatology, as an emollient (moisturiser)
Surfing, for grip on surfboards as a component of surfwax.
The primary component of glide wax, used on skis and snowboards.
As a food additive, a glazing agent with E number E905
The paraffin test is used in forensics to detect granules of gunpowder in the hand of a shooting suspect.

Food-grade paraffin wax is used in some candies to make them look shiny. Although edible, it is nondigestible; it passes right through the body without being broken down. Non-food grade paraffin wax can contain oils and other impurities which may be toxic or harmful.

Impure mixtures of mostly paraffin wax are used in wax baths for beauty and therapy purposes.

Paraffin wax is not used much to make original models for casting, as it is relatively brittle at room temperature and usually cannot be cold-carved without excessive chipping and breaking. Soft, pliable waxes such as beeswax are preferred for modelling.

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