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Paraffin wax

Paraffin wax is a white or colourless soft solid derivable from petroleum, coal or oil shale, that consists of a mixture of hydrocarbon molecules containing between twenty and forty carbon atoms. It is solid at room temperature and begins to melt above approximately ; its boiling point is >. Common applications for paraffin wax include lubrication, electrical insulation, and candles; Raw materials and candles production processes, AECM dyed paraffin wax can be made into crayons. It is distinct from kerosene, another petroleum product that is sometimes called paraffin. Un-dyed, unscented, paraffin candles are odorless, and bluish-white in color. Paraffin wax was first created in 1830 in Germany, and marked a major advancement in candlemaking technology, as it burned more cleanly and reliably than tallow candles, and was cheaper to produce. In chemistry, paraffin is used synonymously with alkane, indicating hydrocarbons with the general formula CnH2n+2. The name is derived from Latin parum ("barely") + affinis, meaning "lacking affinity" or "lacking reactivity", referring to paraffin's unreactive nature.

Properties

Paraffin wax is mostly found as a white, odorless, tasteless, waxy solid, with a typical melting point between about , This can vary widely, even outside the quoted range, according to such factors as oil content and crystalline structure. and a density of around 900 kg/m3.{{cite web | last =Kaye | first =George William Clarkson | authorlink = |author2=Laby,Thomas Howell |authorlink2=T. H. Laby | title =Mechanical properties of materials | work =Kaye and Laby Tables of Physical and Chemical Constants | publisher = National Physical Laboratory | url =http://www.kayelaby.npl.co.uk/general_physics/2_2/2_2_1.html | doi = |deadurl=no |accessdate=25 October 2013}} It is insoluble in water, but soluble in ether, benzene, and certain esters. Paraffin is unaffected by most common chemical reagents but burns readily. Its heat of combustion is 42 MJ/kg. Paraffin wax is an excellent electrical insulator, with a resistivity of between 1013 and 1017 ohm metre.{{cite web | last = | first = | authorlink = | title =Electrical insulating materials | work =Kaye and Laby Tables of Physical and Chemical Constants | publisher =National Physical Laboratory | year =1995 | url =http://www.kayelaby.npl.co.uk/general_physics/2_6/2_6_3.html | doi = |deadurl=no |accessdate=25 October 2013}} This is better than nearly all other materials except some plastics (notably Teflon). It is an effective neutron moderator and was used in James Chadwick's 1932 .{{cite web | last = | first = | authorlink = | title =Attenuation of fast neutrons: neutron moderation and diffusion | work =Kaye and Laby Tables of Physical and Chemical Constants | publisher =National Physical Laboratory | url =http://www.kayelaby.npl.co.uk/atomic_and_nuclear_physics/4_7/4_7_3.html | doi = |deadurl=no |accessdate=25 October 2013}}{{cite book | last =Rhodes | first =Richard | authorlink =Richard Rhodes | title =The Making of the Atomic Bomb | publisher =Simon and Schuster | year =1981 | location =New York | page = 163 | url = | doi = | isbn =0-671-44133-7}} Paraffin wax is an excellent material for storing heat, with a specific heat capacity of 2.14–2.9 J g−1 K−1 ( joules per gram kelvin) and a heat of fusion of 200–220 J g−1.{{cite web | last = | first = | authorlink = | title =Specific Heat Capacity | work =Diracdelta.co.uk Science and Engineering Encyclopedia | publisher =Dirac Delta Consultants Ltd, Warwick, England | url =http://www.diracdelta.co.uk/science/source/s/p/specific%20heat%20capacity/source.html | doi = |deadurl=no |accessdate=25 October 2013}} This property is exploited in modified drywall for home building material: a certain type of wax (with the right melting point) is infused in the drywall during manufacture so that it melts during the day, absorbing heat, and solidifies again at night, releasing the heat. Paraffin wax phase-change cooling coupled with retractable radiators was used to cool the electronics of the Lunar Rover. Wax expands considerably when it melts and this allows its use in wax element thermostats for industrial, domestic and, particularly, automobile purposes. Wax-pellet thermostat United States Patent 4948043
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This article based upon the http://en.wikipedia.org/wiki/Paraffin_wax, the free encyclopaedia Wikipedia and is licensed under the GNU Free Documentation License.
Further informations available on the list of authors and history: http://en.wikipedia.org/w/index.php?title=Paraffin_wax&action=history
presented by: Ingo Malchow, Mirower Bogen 22, 17235 Neustrelitz, Germany