Methane

Molecular Formula: CH₄
Molecular Mass: 16

Methane gas was discovered by the Italian scientist Alessandro Volta between 1776 and 1778 while he was studying the gases found in marshy land.

Occurrence:

• Methane occurs in natural gas to the extent of 87%.
• Decomposition of organic matter in the absence of air (anaerobic) produces methane.
• Methane is present in biogas.
• Methane is found in coal mines.
• Methane is found at the surface of marshy places, which is why it is also called marsh gas.
• On heating a mixture of hydrogen and carbon monoxide gases at 300°C in the presence of nickel (catalyst), methane gas is formed.
• Fractional distillation of natural gas gives methane in pure form.

Physical Properties of Methane

• The melting point of methane is -182.5°C.
• The boiling point of methane is -161.5°C.
• It is a colourless gas.
• The density of liquid methane is less than that of water.
• Methane is sparingly soluble in water. It is highly soluble in organic solvents like gasoline, ether, and alcohol.
• Methane is in a gaseous state at room temperature.

Chemical Properties of Methane

• Highly Inflammable: Methane burns by reacting with oxygen to give a bluish flame. In this reaction, 213 kcal/mol of heat is given out. Methane burns completely.
  Chemical Reaction: CH₄ + 2O₂ → CO₂ + 2H₂O + heat
• Chlorination: Methane and chlorine gases react with each other at a temperature of 250°C to 400°C in the presence of ultraviolet light and form mainly methyl chloride (chloromethane) and hydrogen chloride. This reaction is called the chlorination of methane.
  Chemical Reaction: CH₄ + Cl₂ → CH₃Cl + HCl

1. Methane, found in natural gas, is widely used in industries like fabric mills, paper mills, food processing, and petrol purification.
2. Its combustion releases a smaller proportion of CO₂ compared to other hydrocarbons, making it an eco-friendly domestic fuel.
3. Methane serves as a key raw material for producing organic compounds like ethanol, methyl chloride, methylene chloride, and acetylene.
4. It is used to generate electricity in power plants due to its high energy yield.
5. Methane is a primary component of compressed natural gas (CNG), used as a cleaner alternative fuel for vehicles.
6. It is a crucial feedstock in hydrogen production through steam reforming processes.
7. Biogas plants capture and utilise methane gas that is naturally produced when organic waste breaks down in an oxygen-free environment (anaerobic digestion). This methane is then used as a renewable energy source for purposes like cooking, heating, or generating electricity.