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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Ball-and-stick

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

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.

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