Methane (CH₄)

Methane (CH₄)

The first member in the homologous series of alkanes.

Chemistry

Keywords

methane, saturated hydrocarbon, alkane, paraffin, homologous series, petroleum, natural gas, firedamp, tetrahedron, nonpolar, thermal decomposition, substitution reaction, organic chemistry, chemistry

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Methane CH₄

Information

Molar mass: 16.043 g/mol

Melting point: -182.47 °C

Boiling point: -161.45 °C

Density: 0.0007 g/cm³

Relative steam density (air=1): 0.6

Heat of combustion: 890.9 kJ/mol

Molecular shape: tetrahedron

Bond angle: 109.5°

Properties

Methane is a colourless, odourless, lighter-than-air gas, which dissolves well in organic solvents but not in water. It burns in air to form water and carbon-dioxide. The carbon-hydrogen bond is weakly polar, yet the molecule, due to its symmetry, is non-polar. When it is chlorinated, it produces chloromethane, dichloromethane, trichloromethane and carbon tetrachloride. This is a substitution reaction.

A mixture of methane and air is explosive. (This is called firedamp.) Isolated from air, methane starts to break down at a temperature of about 500 °C. Its reaction with water produces synthesis gas, which is a mixture of carbon monoxide and hydrogen.

Occurrence and production

Methane occurs in natural gas, in swamp gas, in biogas, and, in dissolved form, in crude oil. It is a product of the bacterial decomposition of cellulose.

It can be produced in laboratories by heating a finely powdered mixture of sodium acetate and sodium hydroxide.

Uses

Methane is an important base material in industry. Various compounds such as halogenated hydrocarbons, acetylene and hydrogen cyanide can be produced from it. It is most widely used as a fuel and a propellant.

Space-filling

Narration

Related items

Alkanes

Alkanes are saturated hydrocarbons which can be organised into a homologous series.

Biogas power plant

Biogas can be produced from organic material (manure, plant waste, organic waste) using bacteria. Biogas is a mixture of methane and carbon dioxide; burning...

Methane hydrate

A solid substance formed at low temperatures on the ocean floors of Earth by the high pressure.

Chlorination of methane by a substitution reaction

During the substitution reaction the hydrogen atoms of methane are substituted with chlorine atoms, the by-product is hydrogen chloride.

Acetic acid (ethanoic acid) (CH₃COOH)

One of the products of the oxidation of ethanol.

Bromofluorochloromethane (CHClBrF)

The molecule has two enantiomers: stereoisomers that are mirror images of each other and are not superimposable.

Carbon tetrachloride (CCl₄)

Colourless, toxic liquid with a sweet odour.

Chloromethane (methyl-chloride) (CH₃Cl)

Chloromethane can be prepared by heating a mixture of methane and chlorine.

Dichloromethane (CH₂Cl₂)

It is produced by treating methane with chlorine gas and used as a solvent.

Ethanol (ethyl alcohol) (C₂H₅OH)

The best known alcohol, important in the food industry.

Formamide (methanamide) (HCONH₂)

A colourless, slightly viscous, hygroscopic liquid used in the production of formic acid, hydrogen cyanide and other organic compounds.

Formic acid (methanoic acid) (HCOOH)

Formic acid is the simplest carboxylic acid.

Methanol (methyl alcohol) (CH₃OH)

The simplest saturated alcohol. A highly toxic compound, easily confusable with ethanol.

Methyl formate (C₂H₄O₂)

The ester of formic acid and methanol, an aroma compound found in certain fruits.

Trichloromethane, chloroform (CHCl₃)

Also known as chloroform, used as a solvent in laboratories, earlier as an anaesthetic.

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