hydrocarbon n : an organic compound containing only carbon and hydrogen
EtymologyA portmanteau of hydrogen (hydro-) and carbon.
compound of carbon and hydrogen
- Dutch: koolwaterstof
- Finnish: hiilivety
- Icelandic: vetniskol, kolvatnsefni, kolvetni
- Japanese: 炭化水素
- Latvian: ogļūdeņradis
- Spanish: hidrocarburo
- Swedish: kolväte
In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. With relation to chemical terminology, aromatic hydrocarbons or arenes, alkanes, alkenes and alkyne-based compounds composed entirely of carbon or hydrogen are referred to as "pure" hydrocarbons, whereas other hydrocarbons with bonded compounds or impurities of sulphur or nitrogen, are referred to as "impure", and remain somewhat erroneously referred to as hydrocarbons.
Hydrocarbons are referred to as consisting of a "backbone" or "skeleton" composed entirely of carbon and hydrogen and other bonded compounds, and lack a functional group that generally facilitates combustion without adverse effects.
The majority of hydrocarbons found naturally occur in crude oil, where decomposed organic matter provides an abundance of carbon and hydrogen which, when bonded, can catenate to form seemingly limitless chains.
Types of hydrocarbonsThe classifications for hydrocarbons defined by IUPAC nomenclature of organic chemistry are as follows:
- Saturated hydrocarbons (alkanes) are the most simple of the hydrocarbon species and are composed entirely of single bonds and are saturated with hydrogen; they are the basis of petroleum fuels and are either found as linear or branched species of unlimited number. The general formula for saturated hydrocarbons is CnH2n+2 (assuming non-cyclic structures).
- Unsaturated hydrocarbons have one or more double or triple bonds between carbon atoms. Those with one double bond are called alkenes, with the formula CnH2n (assuming non-cyclic structures). Those containing triple bonds are called alkynes, with general formula CnH2n-2.
- Cycloalkanes are hydrocarbons containing one or more carbon rings to which hydrogen atoms are attached. The general formula for a saturated hydrocarbon containing one ring is CnH2n
- Aromatic hydrocarbons, also known as arenes, are hydrocarbons that have at least one aromatic ring.
Hydrocarbons can be gases (e.g. methane and propane), liquids (e.g. hexane and benzene), waxes or low melting solids (e.g. paraffin wax and naphthalene) or polymers (e.g. polyethylene, polypropylene and polystyrene).
General propertiesBecause of differences in molecular structure, the empirical formula remains different between hydrocarbons; in linear, or "straight-run" alkanes, alkenes and alkynes, the amount of bonded hydrogen lessens in alkenes and alkynes due to the "self-bonding" or catenation of carbon preventing entire saturation of the hydrocarbon by the formation of double or triple bonds.
This inherent ability of hydrocarbons to bond to themselves is referred to as catenation, and allows hydrocarbon to form more complex molecules, such as cyclohexane, and in rarer cases, arenes such as benzene. This ability comes from the fact that bond character between carbon atoms is entirely non-polar, in that the distribution of electrons between the two elements is somewhat even due to the same electronegativity values of the elements (~0.30), and does not result in the formation of an electrophile.
Generally, with catenation comes the loss of the total amount of bonded hydrocarbons and an increase in the amount of energy required for bond cleavage due to strain exerted upon the molecule; in molecules such as cyclohexane, this is referred to as ring strain, and occurs due to the "destabilized" spatial electron configuration of the atom.
In simple chemistry, as per valence bond theory, the carbon atom must follow the "4-hydrogen rule", which states that the maximum number of atoms available to bond with carbon is equal to the number of electrons that are attracted into the outer shell of carbon. In terms of shells, carbon consists of an incomplete outer shell, which comprises 4 electrons, and thus has 4 electrons available for covalent or dative bonding.
According thermodynamics studies hydrocarbons are stable in great depths within the earth. Hydrocarbons also have great abundance in the universe. In Titan (a Saturn moon) there are lakes and seas of liquid methane and ethane confirmed by Cassini-Huygens Mission.
Simple hydrocarbons and their variations
UsageHydrocarbons are one of the Earth's most important energy resources. The predominant use of hydrocarbons is as a combustible fuel source.
Mixtures of volatile hydrocarbons are now used in preference to the chlorofluorocarbons as a propellant for aerosol sprays, due to chlorofluorocarbons impact on the ozone layer.
Burning hydrocarbonsmainarticle Combustion Hydrocarbons are currently the main source of the world’s electric energy and heat sources (such as home heating) because of the energy produced when burnt. Often this energy is used directly as heat such as in home heaters, which use either oil or natural gas. The hydrocarbon is burnt and the heat is used to heat water, which is then circulated. A similar principle is used to create electric energy in power plants.
As methane only releases one carbon dioxide for two water molecules, it is considered the cleanest fuel.
PetroleumLiquid geologically-extracted hydrocarbons are referred to as petroleum (literally "rock oil") or mineral oil, while gaseous geologic hydrocarbons are referred to as natural gas. All are significant sources of fuel and raw materials as a feedstock for the production of organic chemicals and are commonly found in the Earth's subsurface using the tools of petroleum geology.
The extraction of liquid hydrocarbon fuel from a number of sedimentary basins has been integral to modern energy development. Hydrocarbons are mined from tar sands, oil shale and potentially extracted from sedimentary methane hydrates. These reserves require distillation and upgrading to produce synthetic crude and petroleum.
Oil reserves in sedimentary rocks are the principal source of hydrocarbons for the energy, transport and petrochemical industries. Hydrocarbons are of prime economic importance because they encompass the constituents of the major fossil fuels (coal, petroleum, natural gas, etc.) and plastics, paraffin, waxes, solvents and oils. In urban pollution, these components--along with NOx and sunlight--all contribute to the formation of tropospheric ozone.
- McMurry, J. (2000). Organic Chemistry 5th ed. Brooks/Cole: Thomson Learning.
- Clayden, J., Greeves, N., et al. (2000) Organic Chemistry Oxford.
hydrocarbon in Arabic: هيدروكربون
hydrocarbon in Bulgarian: Въглеводород
hydrocarbon in Catalan: Hidrocarbur
hydrocarbon in Czech: Uhlovodíky
hydrocarbon in Welsh: Hydrocarbon
hydrocarbon in Danish: Kulbrinte
hydrocarbon in German: Kohlenwasserstoffe
hydrocarbon in Estonian: Süsivesinikud
hydrocarbon in Spanish: Hidrocarburo
hydrocarbon in Esperanto: Hidrokarbono
hydrocarbon in Persian: هیدروکربن
hydrocarbon in French: Hydrocarbure
hydrocarbon in Irish: Hidreacarbón
hydrocarbon in Galician: Hidrocarburo
hydrocarbon in Hindi: हाइड्रोकार्बन
hydrocarbon in Korean: 탄화수소
hydrocarbon in Croatian: Ugljikovodici
hydrocarbon in Ido: Hidrokarbido
hydrocarbon in Indonesian: Hidrokarbon
hydrocarbon in Icelandic: Kolvetni
hydrocarbon in Italian: Idrocarburi
hydrocarbon in Hebrew: פחמימן
hydrocarbon in Latvian: Ogļūdeņraži
hydrocarbon in Lithuanian: Angliavandenilis
hydrocarbon in Macedonian: Јаглеводород
hydrocarbon in Malay (macrolanguage): Hidrokarbon
hydrocarbon in Mongolian: Нүүрсустөрөгч
hydrocarbon in Dutch: Koolwaterstof
hydrocarbon in Japanese: 炭化水素
hydrocarbon in Norwegian: Hydrokarbon
hydrocarbon in Norwegian Nynorsk: Hydrokarbon
hydrocarbon in Polish: Węglowodór
hydrocarbon in Portuguese: Hidrocarboneto
hydrocarbon in Romanian: Hidrocarbură
hydrocarbon in Russian: Углеводороды
hydrocarbon in Simple English: Hydrocarbon
hydrocarbon in Slovak: Uhľovodík
hydrocarbon in Slovenian: Ogljikovodiki
hydrocarbon in Serbian: Угљоводоник
hydrocarbon in Sundanese: Hidrokarbon
hydrocarbon in Finnish: Hiilivety
hydrocarbon in Swedish: Kolväte
hydrocarbon in Tamil: ஹைடிரோகார்பன்
hydrocarbon in Thai: ไฮโดรคาร์บอน
hydrocarbon in Vietnamese: Hyđrocacbon
hydrocarbon in Turkish: Hidrokarbon
hydrocarbon in Ukrainian: Вуглеводні
hydrocarbon in Chinese: 烃