Methane is the first member of the alkanes group. It is a gas at ordinary temperature. This gas is produced in the form of bubbles from the rotting of vegetation in marshy places.
Hence it is also called Marsh Gas. This gas is also present in gaseous mixtures from volcanoes and in coal mines. Burning a mixture of Methane and Air causes an explosion and ignites. This explosion can also occur under the influence of high pressure.
Therefore, there is a risk of explosion and fire due to presence of methane gas in coal mines. Therefore, methane gas in coal mines is called fire damp. The most prominent source of methane is natural gas. The gaseous mixture obtained from the petroleum well is called natural gas. It has 80%-90% methane gas.
In one section of methane, one carbon atom is attached to four hydrogen atoms by four single binds. It has four co-connective bonds and these four bonds are sigma bound(σ). Its shape is tetrahedral and the angle between two C-H binds is 109°. The carbon atom present in it is of hybrid sp3 type.
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Preparation of Methane
Preparation The method of making methane is similar to the common methods of making alkanes group. Some of these methods are used to make methane in the laboratory. Following are the major laboratory methods of manufacturing methane.
Sodium Acetate
Methane gas can be made in the laboratory by heating a mixture of anhydrous sodium acetate and soda lime. In this mixture sodium acetate and soda lime are taken in about 1:2 ratio.
CH3COONa + NaOH → Na2CO3 + CH4
Soda lime is made by heating one part of caustic soda and three parts of quenched lime. It contains NaOH and CaO. NaOH participates in the reaction and prevents the glass equipment used for the CaO reaction from being degraded by NaOH.
The methane obtained by this method collects the gas over water. It contains ethylene and hydrogen gas present as impurities. To remove impurities, impure gas flows through a potassium permanganate solution. Thus pure methane gas is obtained.
Methyl iodide(Iodomethane)
Methane gas is obtained by reduction of methyl iodide by nascent hydrogen. Nascent hydrogen is produced by the reaction of the zinc copper pair on alcohol. Pure methane collects the gas over water.
CH3I + 2H → CH4 + HI
Aluminum Carbide
The reaction of water or dilute hydrochloric acid on aluminium carbide gives methane gas at room temperature. They collect it over water. Hydrogen gas is present as impure in it.
Al4C3 + 12H2O → 3CH4 + 4Al(OH)3
Physical Properties
It is a colorless, odorless, tasteless gas. It is soluble in water but dissolves in sufficient amount in alcohol and ether. It is lighter than air. It has a boiling point of -162°C and a melting point of -184°C at normal pressure. It can be liquefied at 11°C at 180 atmospheric pressure.
Chemical Properties
Methane is the first member of the alkane group and exhibits common properties of the alkane group. On chlorination, a mixture of methyl chloride is obtained. It cannot be nitrated or sulfurized. On complete combustion, this gas produces carbon dioxide gas and water vapour.
On incomplete combustion, carbon mono oxide gas or carbon black is formed. Methane alcohol and formaldehyde can be formed upon oxidizing it in the presence of a catalyst. Since it does not show yogic isomerism, it is not possible to synchronize. Its aromatization or heat decomposition also cannot be done.
Methane Gas Uses
It is used as a fuel as the main ingredient of natural gas.
Carbon black is used to make. Carbon black is used to make raid ink, shoe polish, gramophone records, and rubber tires.
Synthesis gas is obtained when a mixture of methane and water vapour flows over the mixture in heated nickel and alumina at 800°C.
CH4 + H2O → CO + 3H2
It is used in the industrial manufacture of methanol. Synthesis gas is also used in the synthesis of some other compounds.
Some other organic compounds such as formaldehyde, methyl chloride and dichloromethane are also made from methane.
