Natural Sources of Methane Emission
Methane also called marsh gas is the simplest hydrocarbon compound of the paraffin group that occurs in natural gas sources and emission from the oil-wells having molecular formula CH4 with regular tetrahedral chemical structure. A methane molecule is an important chemical product of organic decay in swamps and marshes. Therefore, methane gas is produced by the action of bacteria on swamps and marshes in our environment and name as marsh gas. Sewage sludge fermented by catalyst bacteria yields methane gas about 70 percent and also forms 40 percent by volume in coal gas, uses as a liquid fuel in our everyday life responsible for global warming, and acts as greenhouse gases.
Structural Formula of CH4 Molecule
Marsh gas having the common name methane (CH4) is the simplest natural unsaturated hydrocarbon compound in an olefin series with the molecular formula CH4 and molecular weight 16 gm mol-1. If we assuming the quadrivalence of carbon atom it shows the following structure in chemistry or chemical science. The carbon atom in methane has 2s1 2px1 2py1 2pz1 electronic configuration. On mixing these four atomic orbitals give four equivalent sp3-hybrid orbitals. These hybridized orbitals are directed towards the corner of the regular tetrahedron showing in the above picture. Each of these half-filled hybrid orbitals of carbon atom bonding with half-filled atomic orbitals of the hydrogen atom. Therefore, the methane molecule has a tetrahedral shape with the C-H-C bond angle of 109.5°.
Properties of hydrogen atom in four H-C-H bonds are equivalent with no dipole moment. Therefore, the bond angle, bond energy, and bond length of all carbon hydrogen bond are equivalent in the CH4 molecule.
Chemical Production Process of Methane
Methane is the main part of natural marsh gas synthesized by striking electric between carbon electrodes in atmosphere hydrogen or by heating carbon mixture with the chemical element nickel at 475°C in the presence of hydrogen. Sabatier and Senderens in 1897 invented the equation for methane production by passing a mixture of hydrogen and carbon monoxide or carbon dioxide over finely divided elements like nickel at about 300°C.
CO + 3H2 → CH4 + H2O
CO2 + 4H2 → CH4 + 2H2O
Methane is generally prepared by heating a 1:3 chemical composition of sodium acetate and soda-lime or reduction of methyl iodide with dissolving metals or by strong base lithium aluminum hydride. CH3COONa + (NaOH + CaO) → CH4 + Na2CO3
The organic compound methane (CH4) is also prepared by hydrolysis of inorganic solid like aluminum carbide or Grignard reagent (methyl magnesium iodide) by water solution. Al4C3 + 12H2O → 3CH4 + 4Al(OH)3.
Physical and Chemical Properties
At normal temperature, methane (CH4) is a colorless, odorless, non-poisonous gaseous, flammable substances with a boiling point = -164°C and a melting point -184°C in 760 mmHg. This gas is less soluble in water but more soluble in organic solvents (alcohol and ether). Therefore, 100 ml of water used to dissolve about 5 ml of CH4 gas at 20°C. In chemistry, the thermodynamics combustion of the methane (CH4) compound gives non- luminous flame in air or oxygen by forming carbon dioxide and water.
The natural gas explodes violently when mixed with air (oxygen) which causes the explosion in coal mines, where methane is known as fire-damp. On catalytic oxidation, it produces methanol and formaldehyde with decreasing the oxidation number of the carbon atom. But when a mixture of methane and oxygen passing through the element copper tube at 100 atm pressure and 200°C temperature produced the chemical compound methanol.
Uses of Methane Gas in Everyday Life
Methane on heating to 1000°C or by incomplete combustion of the gas produces carbon or a very finely divided state of carbon black that is used in paint, printer ink, and rubber industry for making motor tires. The chemical compound, methane gas also uses as an organic fuel in our everyday life and preparation of methyl chloride, acetylene, formaldehyde, and methanol which use largely in the chemical plants. The synthesis gas is produced when a mixture of methane and steam passed over the heated nickel supported on alumina uses in the chemical industry for the preparation of different chemicals. Methane gas is largely used as a natural source of hydrogen gas in the chemical industry.
Methane in Greenhouse Gases
Now a serious concern about the increase in the use of methane, carbon dioxide, CFC, ozone, nitrous oxide gases, and water vapor of the atmosphere causes to raise the global temperature and the effect is known as the greenhouse effect. But the greenhouse used to maintain in winter counties by artificial heating. The contribution to global warming of CH4 gas is about 16 to 20 percent. Therefore, CH4 heating the earth’s atmosphere by trapping electromagnetic infrared particles or heat reflected from the earth’s surface.
Recently due to many global activities like the industrial revolution and the use of natural gas, the concentration of greenhouse gases increases. The average temperature of the earth’s atmosphere rises about 2.5°C in the next 30 years which resulting in a major climate change in the world. Hence the polar ice caps will melt indirectly by greenhouse gases methane. These consequently increase in sea level. Therefore, many seaside localities including some big Iceland completely submerged. Therefore, to save our civilization use non-fossil fuel meaning wind energy, nuclear power, and decreasing the uses of fossil fuels meaning natural gas (sources of methane), coal, etc.