Difference between revisions of "Hydrocarbon" - New World Encyclopedia

Latest revision as of 13:34, 17 May 2021

Hydrocarbons are obtained by refining petroleum at refineries such as this one.

A hydrocarbon is any chemical compound that is constituted of just the elements carbon (C) and hydrogen (H). Each hydrocarbon molecule consists of a carbon backbone, or "carbon skeleton," with hydrogen atoms attached to that backbone.

Hydrocarbons are among the Earth's most important natural resources. They are currently the main source of the world’s electric energy and heat energy (such as for heating buildings) because they produce large amounts of heat when burned. The gasoline that serves as fuel for automobiles consists primarily of hydrocarbons. In addition, many hydrocarbons serve as base materials for the synthesis of organic chemicals used in the production of consumer products and industrial materials.

Natural occurrence and extraction

Hydrocarbons are the main constituents of petroleum (literally, "rock oil"), also called "oil," and natural gas. They are commonly found in and extracted from the Earth´s subsurface. Petroleum is a mixture of liquid hydrocarbons, while natural gas is mainly constituted of methane gas.

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 and oil shale. These reserves require distillation and upgrading to produce synthetic crude and petroleum. A future source of methane may be methane hydrates found on ocean floors.

Types of hydrocarbons

A model of the alkane known as hexane.

A model of the alkyne called ethyne.

A model of an arene called benzene.

There are essentially three types of hydrocarbons: Saturated hydrocarbons, also known as alkanes: In each molecule of an alkane, the chemical bonds that join the carbon atoms are single covalent bonds. If the alkane molecule includes a ring of carbon atoms (all connected by single covalent bonds), it is called a cycloalkane. Unsaturated hydrocarbons, which are subdivided into two groups:

- alkenes: Each molecule of an alkene contains at least one double covalent bond between carbon atoms.
- alkynes: Each molecule of an alkyne contains at least one triple covalent bond between carbon atoms.
Aromatic hydrocarbons, or arenes: Each molecule of an aromatic hydrocarbon contains at least one aromatic ring, in which the bonds between carbon atoms are aromatic bonds.

When organic compounds are considered in general, saturated and unsaturated hydrocarbons are placed in the category known as aliphatic compounds, while aromatic hydrocarbons are categorized as aromatic compounds.

Some simple hydrocarbons

The simplest hydrocarbon is methane, the main constituent of natural gas. Its chemical formula, CH₄, indicates that each molecule of methane consists of four hydrogen atoms attached to one carbon atom. Ethane, with the formula C₂H₆, is a hydrocarbon (more specifically, an alkane) in which each molecule has two carbon atoms held together with a single covalent bond, and three hydrogen atoms are bound to each carbon atom. Each molecule of propane (C₃H₈) has three carbon atoms, and each molecule of butane (C₄H₁₀) has four carbons.

General chemical formulas

If a hydrocarbon molecule contains "n" carbon atoms, and the type of hydrocarbon is known, its general chemical formula can be written as follows:

Alkane: C_nH_2n+2.
Cycloalkane: C_nH_2n (assuming a single ring, with all the carbon atoms in the ring structure).
Alkene: C_nH_2n (assuming only one double bond in each molecule).
Alkyne: C_nH_2n-2 (assuming only one triple bond in each molecule).
Aromatic ring: C_nH_n (assuming a single ring, with all the carbon atoms in the ring structure).

The above chemical formulas are based on the assumption that each carbon atom forms four covalent bonds, including bonds with hydrogen atoms and other carbon atoms. A double covalent bond counts as two bonds; a triple covalent bond counts as three bonds. A carbon atom in an aromatic ring is a special case and can have only one hydrogen atom attached to it.

Molecular graph

A "molecular graph" of a hydrocarbon is a simple representation of the carbon skeleton of the molecule under consideration. Each line in the molecular graph represents a covalent bond that connects two carbon atoms. Thus, although the graph shows no symbols for carbon atoms, a carbon atom is (by convention) located at each end of each line. The symbols for hydrogen atoms are not shown either, but each carbon atom holds as many hydrogen atoms as it needs to form four covalent bonds.

Uses of hydrocarbons

Most hydrocarbons are combustible. When burned, they produce carbon dioxide, water, and large quantities of heat. This energy is used to heat homes and other buildings and to generate electricity. When heating a home, for example, oil or natural gas is burned and the energy released is used to heat water or air. The hot water or air is then circulated around the building.

A similar principle is used to create electric energy in power plants. A hydrocarbon fuel (such as natural gas) is burned, the energy released is used to convert water into steam, and the steam is used to drive turbines that generate electricity.

Hydrocarbons are also raw materials that serve as feedstock for the production of a wide range of organic chemicals, which in turn are used for such products as plastics, pigments, solvents, pharmaceuticals, and explosives.

Effects on health and the environment

Hydrocarbon vapors can be harmful if inhaled. Moreover, hydrocarbons contribute to the formation of ozone in the troposphere. For these reasons, hydrocarbons in the atmosphere are considered to be pollutants.

Ideally, the combustion of hydrocarbons should produce only carbon dioxide, water, and heat. Yet, incomplete combustion leads to the production of carbon monoxide, a toxic gas. Carbon monoxide binds to hemoglobin (in the blood) more readily than oxygen does; so, when carbon monoxide is inhaled, it blocks oxygen from being absorbed and leads to suffocation. Moreover, the hydrocarbon fuel being burned may contain other substances that are harmful when released.

Moreover, carbon dioxide, a product of the combustion of hydrocarbons, is a greenhouse gas—a gas that helps trap heat in the Earth's atmosphere. This has led to concerns that the excessive burning of hydrocarbon fuels contributes to global warming.

References
ISBN links support NWE through referral fees

McMurry, John. 2004. Organic Chemistry, 6th ed. Belmont, CA: Brooks/Cole. ISBN 0534420052.

Morrison, Robert T., and Robert N. Boyd. 1992. Organic Chemistry, 6th ed. Englewood Cliffs, NJ: Prentice Hall. ISBN 0136436692.

Solomons, T.W. Graham, and Craig B. Fryhle 2004. Organic Chemistry, 8th ed. Hoboken, NJ: John Wiley. ISBN 0471417998.

External links

All links retrieved May 17, 2021.

The Methane Molecule

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+{{Copyedited}}{{Paid}}{{Images OK}}{{Submitted}}{{Approved}}
 [[Image:MiRO1.jpg|thumb|300px|Hydrocarbons are obtained by refining petroleum at refineries such as this one.]]
-In chemical terms, a '''hydrocarbon''' is any [[chemical compound|compound]] that is constituted of just the elements '''[[carbon]]''' (C) and '''[[hydrogen]]''' (H). Each hydrocarbon molecule consists of a carbon backbone, or "carbon skeleton," with hydrogen atoms attached to that backbone.
+A '''hydrocarbon''' is any [[chemical compound]] that is constituted of just the elements [[carbon]] (C) and [[hydrogen]] (H). Each hydrocarbon molecule consists of a carbon backbone, or "carbon skeleton," with hydrogen [[atom|atoms]] attached to that backbone.
+{{toc}}
+Hydrocarbons are among the [[Earth]]'s most important natural resources. They are currently the main source of the world’s electric [[energy]] and heat energy (such as for heating buildings) because they produce large amounts of heat when burned. The gasoline that serves as fuel for automobiles consists primarily of hydrocarbons. In addition, many hydrocarbons serve as base materials for the synthesis of [[organic chemistry|organic chemicals]] used in the production of consumer products and industrial materials.
-Hydrocarbons are among the [[Earth]]'s most important natural resources. They are currently the main source of the world’s electric energy and heat energy (such as for home heating) because they produce a large amount of heat when burnt. The gasoline that serves as fuel for automobiles consists primarily of hydrocarbons. In addition, chemists use many hydrocarbons as building blocks for the synthesis of other organic compounds.
+== Natural occurrence and extraction ==
-== Simple hydrocarbons ==
+Hydrocarbons are the main constituents of [[petroleum]] (literally, "rock oil"), also called "oil," and [[natural gas]]. They are commonly found in and extracted from the Earth´s subsurface. Petroleum is a mixture of liquid hydrocarbons, while natural gas is mainly constituted of [[methane]] gas.
-The simplest hydrocarbon is [[methane]], the main constituent of [[natural gas]]. Its chemical formula, CH<sub>4</sub>, indicates that each molecule of methane consists of four hydrogen atoms attached to one carbon atom. [[Ethane]], with the formula C<sub>2</sub>H<sub>6</sub>, is a hydrocarbon (more specifically, an [[alkane]]) in which each molecule has two carbon atoms held together with a single [[covalent bond]], and three hydrogen atoms are bound to each carbon atom. Each molecule of [[propane]] (C<sub>3</sub>H<sub>8</sub>) has three carbon atoms, and each molecule of [[butane]] (C<sub>4</sub>H<sub>10</sub>) has four carbons.
+The extraction of liquid hydrocarbon [[fuel]] from a number of sedimentary basins has been integral to modern [[energy development]]. Hydrocarbons are [[mining|mined]] from tar sands and oil shale. These reserves require distillation and upgrading to produce synthetic crude and petroleum. A future source of methane may be [[Methane|methane hydrate]]s found on ocean floors.
+== Types of hydrocarbons ==
 {| align="right"
 |-
-| [[Image:Kalottenmodell_Benzol.png|thumb|right|180px|A model of an arene called [[Benzene]]]]
+| [[Image:Kalottenmodell_Hexan.png|thumb|right|180px|A model of the alkane known as ''hexane''.]]
 |-
-| [[Image:Kalottenmodell_Hexan.png|thumb|right|180px|A model of the alkane known as [[Hexane]]]]
+| [[Image:Kalottenmodell_Ethin.png|thumb|right|180px|A model of the alkyne called ''ethyne''.]]
 |-
-| [[Image:Kalottenmodell_Ethin.png|thumb|right|180px|A model of the alkyne called [[Ethyne]]]]
+| [[Image:Kalottenmodell_Benzol.png|thumb|right|180px|A model of an arene called ''benzene''.]]
 |}
-== Types of hydrocarbons ==
+There are essentially three types of hydrocarbons:
+Saturated hydrocarbons, also known as [[alkane]]s: In each molecule of an alkane, the [[chemical bond]]s that join the carbon atoms are single [[covalent bond]]s. If the alkane molecule includes a ring of carbon atoms (all connected by single covalent bonds), it is called a cycloalkane.
+Unsaturated hydrocarbons, which are subdivided into two groups:
+#*[[alkenes]]: Each molecule of an alkene contains at least one double covalent bond between carbon atoms.
+#*[[alkynes]]: Each molecule of an alkyne contains at least one triple covalent bond between carbon atoms.
+#[[Aromatic hydrocarbon]]s, or [[arenes]]: Each molecule of an aromatic hydrocarbon contains at least one [[aromatic ring]], in which the bonds between carbon atoms are [[aromatic bond]]s.
+When organic compounds are considered in general, saturated and unsaturated hydrocarbons are placed in the category known as ''aliphatic compounds'', while aromatic hydrocarbons are categorized as ''aromatic compounds''.
+=== Some simple hydrocarbons ===
+The simplest hydrocarbon is [[methane]], the main constituent of [[natural gas]]. Its chemical formula, CH<sub>4</sub>, indicates that each molecule of methane consists of four hydrogen atoms attached to one carbon atom. [[Ethane]], with the formula C<sub>2</sub>H<sub>6</sub>, is a hydrocarbon (more specifically, an [[alkane]]) in which each molecule has two carbon atoms held together with a single [[covalent bond]], and three hydrogen atoms are bound to each carbon atom. Each molecule of [[propane]] (C<sub>3</sub>H<sub>8</sub>) has three carbon atoms, and each molecule of [[butane]] (C<sub>4</sub>H<sub>10</sub>) has four carbons.
-There are essentially three types of hydrocarbons:
+=== General chemical formulas ===
-#[[Saturated hydrocarbon]]*s, also known as '''[[alkane]]s''': In each molecule of an alkane, the [[chemical bond]]s that join the carbon atoms are single [[covalent bond]]s. If the alkane molecule includes a ring of carbon atoms (all connected by single covalent bonds), it is called a '''cycloalkane'''.
-#[[Unsaturated hydrocarbon]]*s, which are subdivided into two groups:
-#*'''[[alkene]]s''': Each molecule of an alkene contains at least one double [[covalent bond]] between carbon atoms.
-#*'''[[alkyne]]s''': Each molecule of an alkyne contains at least one triple [[covalent bond]] between carbon atoms.
-#[[Aromatic hydrocarbon]]*s: Each molecule of an aromatic hydrocarbon contains at least one [[aromatic ring]], in which the bonds between carbon atoms are [[aromatic bond]]s.
-=== The number of hydrogen atoms ===
+If a hydrocarbon molecule contains "n" carbon atoms, and the type of hydrocarbon is known, its general chemical formula can be written as follows:
+*Alkane: C<sub>''n''</sub>H<sub>''2n+2''</sub>.
+*Cycloalkane: C<sub>''n''</sub>H<sub>''2n''</sub> (assuming a single ring, with all the carbon atoms in the ring structure).
+*Alkene: C<sub>''n''</sub>H<sub>''2n''</sub> (assuming only one double bond in each molecule).
+*Alkyne: C<sub>''n''</sub>H<sub>''2n-2''</sub> (assuming only one triple bond in each molecule).
+*Aromatic ring: C<sub>''n''</sub>H<sub>''n''</sub> (assuming a single ring, with all the carbon atoms in the ring structure).
-The number of hydrogen atoms in hydrocarbons can be determined, if the number of carbon atoms is known, by using these following equations:
+The above chemical formulas are based on the assumption that each carbon atom forms four covalent bonds, including bonds with hydrogen atoms and other carbon atoms. A double covalent bond counts as two bonds; a triple covalent bond counts as three bonds. A carbon atom in an aromatic ring is a special case and can have only one hydrogen atom attached to it.
-*[[Alkane]]s: C<sub>''n''</sub>H<sub>''2n+2''</sub>
-*[[Alkene]]s: C<sub>''n''</sub>H<sub>''2n''</sub> (assuming only one double bond)
-*[[Alkyne]]s: C<sub>''n''</sub>H<sub>''2n-2''</sub> (assuming only one triple bond)
-*[[Cyclic hydrocarbon]]s: C<sub>''n''</sub>H<sub>''2n''</sub>
-Each of these hydrocarbons must follow the 4-hydrogen rule which states that all carbon atoms must have the maximum number of hydrogen atoms that it can hold (the limit is four). A carbon atom has a bonding capacity of 4 and therfore must make 4 bonds, whether it be with hydrogen or an ajoining carbon atom. Note, an extra bond removes 2 hydrogen atoms and only saturated hydrocarbons can attain the full four. This is because of the unique positions of the carbon's four electrons.
-== Molecular graph==
+=== Molecular graph ===
-Usually carbon backbone is represented as molecular [[graph theory|graph]] in which only carbon atoms are represented as [[vertex|vertices]] and bonds as [[edge]]s. [[Molecular graph]]s contain the structure of the hydrocarbon in which missing hydrogen atoms can be added in a unique way.  Hydrocarbons are extensively studied in [[mathematical chemistry]].
-== Petroleum ==
+A "molecular graph" of a hydrocarbon is a simple representation of the carbon skeleton of the molecule under consideration. Each line in the molecular graph represents a covalent bond that connects two carbon atoms. Thus, although the graph shows no symbols for carbon atoms, a carbon atom is (by convention) located at each end of each line. The symbols for hydrogen atoms are not shown either, but each carbon atom holds as many hydrogen atoms as it needs to form four covalent bonds.
-Liquid 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 chemistry|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 basin]]s has been integral to modern [[energy development]]. Hydrocarbons are [[mining|mined]] from [[tar sands]], [[oil shale]] and potentially extracted from sedimentary [[methane hydrate]]s. These reserves require distillation and upgrading to produce [[synthetic crude]] and petroleum.
+==Uses of hydrocarbons==
-[[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 fuel]]s ([[coal]], [[petroleum]], [[natural gas]], etc.) and [[biofuel]]s, as well as [[plastic]]s, [[paraffin]], [[wax]]es, [[solvent]]s and oils. In urban [[pollution]], these components—along with NOx and [[sunlight]]—all contribute to the formation of [[tropospheric ozone]].
+Most hydrocarbons are combustible. When burned, they produce carbon dioxide, water, and large quantities of heat. This energy is used to heat homes and other buildings and to generate electricity. When heating a home, for example, oil or natural gas is burned and the energy released is used to heat water or air. The hot water or air is then circulated around the building.
-The concentration of hydrocarbon vapours can be harmful if inhaled.
+A similar principle is used to create electric energy in [[power plants]]. A hydrocarbon fuel (such as natural gas) is burned, the energy released is used to convert water into [[steam]], and the steam is used to drive [[turbine]]s that generate electricity.
-== Burning hydrocarbons ==
+Hydrocarbons are also raw materials that serve as [[feedstock]] for the production of a wide range of organic chemicals, which in turn are used for such products as plastics, pigments, solvents, pharmaceuticals, and explosives.
-Most hydrocarbons are combustible. When burnt, they produce carbon dioxide, water, and a lot of heat. We rely on this energy to heat our homes (and other buildings) and to generate electricity. When heating a home, for example, oil or natural gas is burnt and the energy released is used to heat water or air. The hot water or air is then circulated around the building. A similar principle is used to create electric energy in [[power plants]]. Hydrocarbons (usually [[coal]]) are burnt and the energy released in this way is used to turn water into [[steam]], which is used to turn a [[turbine]] that generates energy.
+== Effects on health and the environment ==
-In an ideal reaction, the waste would be only water and carbon dioxide but because the coal is not pure or clean there are often many toxic byproducts such as [[Mercury (element)|mercury]] and [[arsenic]]. Also, incomplete [[combustion]] causes the production of carbon monoxide which is toxic because it will bind with [[hemoglobin]] more readily than oxygen, so if it is breathed in, oxygen can not be absorbed, causing suffocation. Incomplete [[combustion]] also has a byproduct of [[carbon]] in the form of [[soot]].
+Hydrocarbon vapors can be harmful if inhaled. Moreover, hydrocarbons contribute to the formation of [[ozone]] in the [[Earth's atmosphere|troposphere]]. For these reasons, hydrocarbons in the atmosphere are considered to be pollutants.
-Coal reserves will last for decades and possibly beyond [[2100]]. Mostly in response to [[climate change|climate concerns]], [[clean coal]] [[technology]] is currently under [[technology development|development]]. For example, the [[United Kingdom|UK]] and [[China]] have signed an [[agreement]] to develop such technology with carbon dioxide emissions capture and storage in both China and the [[EU]] by [[2020]]. Similar research is being conducted in the [[United States|U.S.]] and other countries.  By some, hydrocarbons in the atmosphere are considered to be dangerous air pollutants.
+Ideally, the combustion of hydrocarbons should produce only carbon dioxide, water, and heat. Yet, incomplete combustion leads to the production of carbon monoxide, a toxic gas. Carbon monoxide binds to [[hemoglobin]] (in the blood) more readily than oxygen does; so, when carbon monoxide is inhaled, it blocks oxygen from being absorbed and leads to suffocation. Moreover, the hydrocarbon fuel being burned may contain other substances that are harmful when released.
-== External links ==
+Moreover, carbon dioxide, a product of the combustion of hydrocarbons, is a greenhouse gas&mdash;a gas that helps trap heat in the [[Earth's atmosphere]]. This has led to concerns that the excessive burning of hydrocarbon fuels contributes to [[global warming]].
-*[http://www.worldofmolecules.com/fuels/methane.htm The Methane Molecule]
-*[http://www.gasresources.net/DisposalBioClaims.htm Dismissal of the Claims of a Biological Connection for Natural Petroleum.]
-* [http://www.poten.com/ut_glossary.asp Poten & Partners: Glossary of Hydrocarbon Terms]
 == See also ==
-*[[Abiogenic petroleum origin]]
-*[[Energy storage]]
+*[[Alkane]]
-*[[Fractional distillation]]
+*[[Alkene]]
-*[[Functional group]]
+*[[Alkyne]]
-*[[Alkanes]]
+*[[Aromatic compound]]
+*[[Natural gas]]
+*[[Petroleum]]
+== References ==
+* McMurry, John. 2004. ''Organic Chemistry,'' 6th ed. Belmont, CA: Brooks/Cole. ISBN 0534420052.
+* Morrison, Robert T., and Robert N. Boyd. 1992. ''Organic Chemistry,'' 6th ed. Englewood Cliffs, NJ: Prentice Hall. ISBN 0136436692.
+* Solomons, T.W. Graham, and Craig B. Fryhle 2004. ''Organic Chemistry,'' 8th ed. Hoboken, NJ: John Wiley. ISBN 0471417998.
+== External links ==
+All links retrieved May 17, 2021.
+* [http://www.worldofmolecules.com/fuels/methane.htm The Methane Molecule]
 [[Category:Physical sciences]]
 [[Category:Chemistry]]
-[[Category:Environmental Chemistry]]
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