Oxford Essays: Hydrocarbons

Hydrocarbons

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HYDROCARBONS

A hydrocarbon is a type of chemical compound. It is made of only hydrogen and carbon atoms. They can be found in crude oil and are separated by fractional distillation (which means they are separated into different groups). The hydrogen and carbon are bonded with non-polar covalent bonds. Because of its lack of polar covalent bonds, hydrocarbons cannot create hydrogen bonds with water and are hydrophobic.

Hydrocarbon "Families"

Hydrocarbons are grouped into "families" or "homologous series". There are five main families. The hydrocarbons in each family have a general formula and similar chemical properties, and similar trends in physical properties.

Alkanes

Alkanes are the simplest hydrocarbons. Their general formula is CnH2n+2.

Alkane Name Formula
Methane: CH4
Ethane: C2H6
Propane: C3H8
Butane: C4H10
Pentane C5H12
Hexane C6H14
Heptane C7H16
Octane C8H18
Nonane C9H20
Decane C10H22

Alkenes

Alkenes are similar to alkanes. The main difference between them is that alkenes have a carbon to carbon double bond. The general formula for the alkenes is CnH2n.

Alkene Name Formula
Ethene C2H4
Propene C3H6
Butene C4H8
Pentene C5H10
Hexene C6H12
Heptene C7H14
Octene C8H16
Nonene C9H18
Decene C10H20
Note that there is no "Methene". Methene is not possible as alkenes require a carbon-carbon double bond and methane only has one carbon atom.

Alkynes

Alkynes have a carbon to carbon triple bond. CnH2n-2 is their general formula.

Alkyne Name Formula
Ethyne C2H2
Propyne C3H4
Butyne C4H6
Pentyne C5H8
Hexyne C6H10
Heptyne C7H12
Octyne C8H14
Nonyne C9H16
Decyne C10H18

"Methyne" does not exist because of methane's one carbon atom.

Cycloalkanes

Cycloalkanes are isomers of alkenes. They have the same general formula (CnH2n), the only difference is that they do not have a carbon to carbon double bond.

Cycloalkane Name Formula
Cyclopropane C3H6
Cyclobutane C4H8
Cyclopentane C5H10
Cyclohexane C6H12
Cycloheptane C7H14
Cycloctane C8H16
Cyclononane C9H18
Cyclodecane C10H20

Note that the alkane Methane and the alkene Ethene do not have a cycloalkane because they can only form a straight line.

Alkadiene

Alkadienes have two carbon to carbon double bonds. Their general formula is CnH2n-2. They are isomers of Alkynes.

Aromatic Hydrocarbons

Aromatic hydrocarbons are aromatic organic molecules that form flat ring-shaped bonds. The most simplest of aromatic hydrocarbons are benzene and indole. They can have one ring, heterocyclic, like benzene or 2 rings, bicyclic like napthalene (primary ingredient in mothballs) or many rings, polycyclic like anthracene (red dye colourant). Their general formula is CnH2n-6, where n is a number greater than or equal to 6.