What is methane gas in organic chemistry?

The first compound in the paraffin or alkene class is methane gas. Methane gas is also known as sweet gas or Marsh gas. Its molecular formula is CH4.

Methane gas is the main component of the natural gas that is obtained from underground oil wells. Methane gas is 90% of natural gas.

Methane gas is also found in coal mines. Coal gas produced as a result of internal distillation of wood also contains about 50% methane gas.

Methane gas is not toxic. It is a colorless, odorless, tasteless gas. Methane gas is much lighter than air. Its vapor density is about half that of air vapor density.

Methane is a non polar gas and hence insoluble in water but soluble in organic solvents, such as, alcohol, ether, benzene, acetone, toluene etc.

When cooled under pressure at critical temperatures, methane gas first becomes liquid and then solid. The melting point of methane gas is 87.2K and the boiling point is 111.6K.

The density of methane gas is 0.66 kg / cubic meter at 25ᵒC temperature and 1 atmosphere pressure.

Read also : What is methanol or methyl alcohol?

Chemical formula and structure

Mass diffraction and other analysis proved that the chemical formula of methane gas is CH4. In methane, the central carbon atom is directly attached with four hydrogen atoms.

The carbon atom in methane is sp3 hybridized. The geometry of the methane molecule is tetrahedral. The H — C — H bond angle is 109ᵒ28’ and C — H bond distance is 1.09Å.

All the four H-atoms in methane are equivalent. Because of substitution of one H- atom by any univalent atom or group give only one mono substituted compound. This implies that all four H-atoms of methane are equivalent.

Methane gas preparation

There are different methods for the preparation of methane gas. Out of them, laboratory method and synthetic method are most important.

Laboratory method

In laboratory method, anhydrous sodium acetate is mixed with dry sodalime by 1:3 rations and then heated. As a result, methane gas is obtained.

CH3COONa +NaOH ⟶ CH4 + Na2CO3

Synthetic method

In this method, a mixture of CO or CO2 and hydrogen is passed over a Ni dust at 573K — 673K temperature and as result of this methane gas is obtained.

CO +3H2 ⟶ CH4 + H2O | CO2 + 4H2 ⟶ CH4 + 2H2O

Others method (room temperature method)

At room temperature, on reduction of CH3-I by ethyl alcohol and Zn-Cu couple pure methane is obtained. Again, methane gas is also prepared by hydrolysis of Al4C3.

CH3-I + Zn + C2H5-OH ⟶ CH4 + Zn (OC2H5I)

What Is Marsh Gas?

The word Mars means rotten swamp. Methane gas is called Marsh gas. This is because methane gas is produced in the decomposition of plants and animals in ponds, beels and wetlands.

That is, methane gas is produced by the bacterial decomposition of cellulose obtained from plants.

What is will-o-the wisp or Aleya?

Many times methane gas is produced as a result of bacterial decomposition of animals with plants in decomposing muddy wetlands.

It also produces small amounts of phosphine and phosphorus dihydride. Phosphorus dihydride is a very flammable substance. It ignites when it comes in contact with air.

As a result, both methane and phosphine are combustible and ignite and produce light. This is called will-o-the wisp or Aleya.

Uses of methane gas

Methane gas is the main component of compressed natural gas (CNG), which is used as an excellent fuel in different sector for different purpose.

As a fuel, methane gas is excellent. This is because methane gas causes less air pollution than other fuels. Again, it has high calorific value.

For this reason, methane gas is used as fuel in ovens, water heaters, furnaces, cars, turbines and other things. It is also used to keep the home warm.

As a major component of CNG, methane gas is important for power generation by burning as fuel in turbines or steam generators. In many cities, methane is piped to households for domestic heating and cooking.

As rocket fuel, methane gives advantage over the production of small exhaust molecules over kerosene.

There are many other uses of methane gas in organic chemistry. For example, CO2 obtained from methane’s heat dissipation is used to make paint, printing inks and to make car tires.

Many necessary chemicals such as methyl chloride, acetylene, formaldehyde and methanol are produced from methane gas.

The synthesis gas (CO + H2) obtained by the reaction of steam with methane is used in the production of methanol and hydrogen gas.