Methane Formula: Structure, Preparation, and Properties

Methane Formula: Do you know which chemical compound is commonly known as Marsh Gas? Which gas forms the major component of natural gas? It is methane, the first member of the homologous alkane series and the simplest hydrocarbon.

Methane is a potent greenhouse gas—about \(28\) times more powerful than carbon dioxide at warming the Earth. It is formed by the decomposition of animals and plants in swampy areas. Methane gas is also a major component of gobar gas, biogas and coal gas. In this article, we will learn more about Methane and Methane formula.

Structure of Methane

Now let us delve deep into the structure and other molecular details of Methane.

Formula

The molecular formula of methane is \({\rm{C}}{{\rm{H}}_4}\). It is a group-\(14\) hydride and the simplest alkane. It is a one-carbon compound in which single bonds attach the carbon to four hydrogen atoms.

Molar Mass

The molar mass of methane, \({\rm{C}}{{\rm{H}}_{\rm{4}}}{\rm{ = Atomic}}\,{\rm{mass}}\,{\rm{of}}\,{\rm{carbon + 4(Atomic}}\,{\rm{mass}}\,{\rm{of}}\,{\rm{hydrogen)}}\)

\({\rm{ = 12}}{\rm{.01u + 4(1}}{\rm{.007u) = 16}}{\rm{.017u}}\)

Hence, one mole of methane weighs 16.01 amu.

Learn Concept of Methanogens

Hybridisation of Methane

Hybridisation is the concept of mixing up atomic orbitals into new hybrid orbitals, which are generally of lower energy and suitable for the pairing of electrons to form chemical bonds. In methane, the carbon atom is \({\rm{S}}{{\rm{p}}^{\rm{3}}}\) hybridised.

\({\rm{S}}{{\rm{p}}^{\rm{3}}}\) Hybridisation

The ground state of carbon has two electrons in its \({\rm{2s}}\) orbital and \(1\) electron each in \({\rm{2Px}}\) and \({\rm{2Py}}\) orbital. The \({\rm{2Pz}}\) orbital is empty. However, in its excited state, one paired electron from the \({\rm{2s}}\) orbital jumps to occupy the empty \({\rm{2Pz}}\) orbital.

Hence, there are four orbitals, \({\rm{2s, 2Px, 2Py}}\), and \({\rm{2Pz}}\), singly paired orbitals that readily accept electrons from other atoms. This overlapping of atomic orbitals results in \({\rm{S}}{{\rm{p}}^{\rm{3}}}\) hybridisation. The presence of these four \({\rm{S}}{{\rm{p}}^{\rm{3}}}\) hybrid orbitals makes carbon tetravalent in nature.

The carbon atom in methane \(\left( {{\rm{C}}{{\rm{H}}_{\rm{4}}}} \right)\) consists of \({\rm{S}}{{\rm{p}}^{\rm{3}}}\) hybridised orbitals. This is diagrammatically represented as below-

Molecular Geometry of Methane

The four hybrid orbitals in methane repel each other and get placed at the corners of a tetrahedron to minimise the force of repulsion between them. Hence, \({{\rm{C}}{{\rm{H}}_{\rm{4}}}}\) has a tetrahedral shape.

Bond Angle

Methane is formed by the overlap of \({\rm{s}}{{\rm{p}}^{\rm{3}}}\) hybrid orbitals of carbon with \({\rm{1s}}\) orbital of hydrogen. This results in the methane molecule having a bond angle of \({\rm{109}}{\rm{.}}{{\rm{5}}^{\rm{o}}}\).

Dipole Moment

The dipole moment of methane \({{\rm{C}}{{\rm{H}}_{\rm{4}}}}\) is zero. Methane is tetrahedral in shape, and due to this structure, each bond pair are at an equal distance from the other. This symmetrical arrangement nullifies the individual bond dipole moment. Hence, the resultant dipole moment of the methane molecule is zero.

Lewis Structure of Methane

Carbon belongs to group \(14\) of the Periodic Table and has \(4\) electrons in its valence shell. These electrons are represented by dots around the chemical symbol of carbon. As there are four valence electrons, it needs four more electrons to complete its octet configuration. This deficiency of four electrons is satisfied by electrons from four hydrogen atoms. The Lewis diagram of \({{\rm{C}}{{\rm{H}}_{\rm{4}}}}\) is shown below.

Skeletal Formula

The \({\rm{s}}{{\rm{p}}^{\rm{3}}}\) hybrid orbitals of carbon form four sigma bonds with four hydrogen atoms. The skeletal formula of \({{\rm{C}}{{\rm{H}}_{\rm{4}}}}\) is shown below.

Three-Dimensional Representation

The Wedge-dash method is used to represent the \({\rm{3 – D}}\) structure of an organic compound. The \({\rm{3 – D}}\) structure of methane has the following aspects-

1. A solid wedge is used to represent a bond that protrudes out of the plane of paper towards the viewer.
2. A dashed wedge is used to represent the bond that projects away from the viewer or into the plane of the paper, and
3. A line is used to represent the bond that lies in the plane of the paper

Preparation of Methane

Laboratory preparation of methane involves heating sodium ethanoate with a mixture of sodium hydroxide, in the presence of a catalyst, calcium oxide. The \({\rm{ – COONa}}\) group from sodium ethanoate is replaced by the hydrogen atom from sodium hydroxide, forming methane, and sodium hydroxide gets converted into sodium carbonate.

Physical Properties of Methane

Chemical Properties of Methane

1. Combustion: Methane undergoes combustion in air and burns with a blue flame to produce carbon dioxide and water. The reaction is as follows-
   \({\rm{C}}{{\rm{H}}_4} + 2{{\rm{O}}_2} \to 2{\rm{C}}{{\rm{O}}_2} + 2{{\rm{H}}_2}{\rm{O}}\)
2. Substitution Reaction: When a mixture of methane and chlorine is exposed to ultraviolet light – typically sunlight – a substitution reaction occurs, and the organic product is chloromethane. This reaction proceeds through a radical mechanism in which hydrogen atoms of the methane molecule are replaced one at a time by chlorine atoms.

Uses of Methane

1. Methane is used as a fuel in cooking because it produces more energy per unit weight in comparison to oil and coal. It is odourless and doesn’t blacken utensils.
2. Methane gas is used to generate electricity for domestic and industrial purposes.
3. Methane gas acts as a starting material to many chemicals such as methanol (methyl alcohol), chloroform etc.
4. It is a common fabric, plastic, anti-freeze and fertiliser ingredient.
5. Methane burns incompletely to form carbon deposits known as carbon black. Carbon black is used to make paints, print ink and strengthen rubber for vehicle tires.
6. Methane gas is used to manufacture ammonia, which is a key compound in the production of fertilisers.
7. Methane leaves no residue making it ideal to be used as rocket fuel.

Methanal

Methanal, commonly known as formaldehyde, is a naturally occurring poisonous gas with a strong, pungent smell. It is colourless, flammable and is the simplest aldehyde produced by the oxidation of methanol in air.

Molecular Formula of Methanal

The chemical formula of Methanal is \({\rm{C}}{{\rm{H}}_{\rm{2}}}{\rm{O}}\) and has a molar mass of \({\rm{30}}{\rm{.026\;g/mL}}\).

Structural Formula of Methanal

Methanal consists of a single carbon atom to which a single bond attaches two hydrogen atoms. An oxygen atom is also bonded to this carbon atom by a double bond.

Hybridisation of the carbon atom = Number of atoms attached + Lone pairs

\( = 3 + 0 = 3\)

The carbon atom of methanal is \({\rm{s}}{{\rm{p}}^{\rm{2}}}\) hybridised \(\left( {{\rm{1\;s + 2P = 3s}}{{\rm{p}}^{\rm{2}}}} \right)\). This means the atomic orbitals of the carbon atom undergo intermixing to form \({\rm{3s}}{{\rm{p}}^{\rm{2}}}\) hybridised orbitals.

The \({\rm{s}}{{\rm{p}}^{\rm{2}}}\) hybridised carbon forms \(3\) sigma bonds. The formation of \(3\) sigma bonds gives Methanal a basic trigonal shape with bond angles of \(120\) degrees. Only two out of three \({\rm{p}}\) orbitals of carbon participate in hybridisation; hence, one \({\rm{p}}\) orbital is unhybridised. This unhybridised \({\rm{p}}\) orbital forms a \({\rm{pi}}\) bond with the unhybridised \({\rm{p}}\) orbital of the oxygen atom. This \({\rm{p}}\) orbital is directed above and below the plane of the paper.

Study Concept of Ammonia

Structure and Formula of Diphenylmethane

Diarylmethane or diphenylmethane is a methane substituted organic compound with the formula \({\left( {{{\rm{C}}_6}{{\rm{H}}_5}} \right)_2}{\rm{C}}{{\rm{H}}_2}\) (often abbreviated \({\rm{C}}{{\rm{H}}_{\rm{2}}}{\rm{P}}{{\rm{h}}_{\rm{2}}}.\) Diphenylmethane is formed when two phenyl groups replace two hydrogen atoms of methane. It is a white solid and is also known as benzhydryl.

It is prepared by the Friedel–Crafts alkylation of benzyl chloride with benzene in the presence of a Lewis acid such as aluminium chloride.

\({{\rm{C}}_6}{{\rm{H}}_6}{\rm{C}}{{\rm{H}}_2}{\rm{Cl}} + {{\rm{C}}_6}{{\rm{H}}_6} \to {\left( {{{\rm{C}}_6}{{\rm{H}}_5}} \right)_2}{\rm{C}}{{\rm{H}}_2} + {\rm{HCl}}\)

The structure of diphenylmethane is as follows:

Summary

In recent years, methane concentrations in the atmosphere have more than doubled. About \(20\% \) of the warming our planet is experiencing now can be attributed to this gas. There’s not much methane in the atmosphere—about \(200\) times less concentrated in the atmosphere than carbon dioxide. But methane’s chemical shape is remarkably effective at trapping heat, which means that adding just a little more methane to the atmosphere can have big impacts on how much and how quickly the planet warms. Hence, it is essential to know its structure and related properties. Through this article, we learned the formula, structure, hybridisation and properties of methane. We also learnt about its uses and some of its derivatives.

FAQs on Methane Formula

The most commonly asked questions on Methane Formula are given below with answers:

Q.1. How is Methane formed?
Ans: Methane is formed when sodium ethanoate is heated with a mixture of sodium hydroxide in the presence of a calcium oxide catalyst.

Q.2. Why is the formula of methane \({\rm{C}}{{\rm{H}}_4}\)?
Ans: Carbon has four valence electrons and needs four more electrons to complete its octet. As it can neither gain nor lose electrons, it shares its electrons with other atoms to a stable noble gas configuration. In methane, the need for four more electrons is fulfilled by the hydrogen atoms; hence the formula is \({\rm{C}}{{\rm{H}}_4}\).

Q.3. Is there a skeletal formula for methane?
Ans: Yes, there is a skeletal formula for methane which is shown below-

Q.4. What is the Lewis structure of methane?
Ans: Carbon belongs to group 14 of the Periodic Table and has 4 electrons in its valence shell. These electrons are represented by dots around the chemical symbol of carbon. As there are four valence electrons, it needs four more electrons to complete its octet configuration. This deficiency of four electrons is satisfied by electrons from four hydrogen atoms. The Lewis diagram of \({\rm{C}}{{\rm{H}}_4}\) is shown below.

Q.5. Why is methane a poor conductor of electricity?
Ans: Methane is a poor conductor of electricity because all bonds in methane molecules are covalent bonds. There is no electron present that can help in the conduction of electricity.

Q.6. What happens when methane is burnt in the air?
Ans: Methane undergoes combustion in the air and burns with a blue flame to produce carbon dioxide and water. The reaction is as follows-

\({\rm{C}}{{\rm{H}}_4} + 2{{\rm{O}}_2} \to 2{\rm{C}}{{\rm{O}}_2} + 2{{\rm{H}}_2}{\rm{O}}\)

Q.7. Draw the electron structure of methane.
Ans: The electron structure of methane is-

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