Question

Pick out the false statement from the following. (1) The namc 'firc damp' is given to methane (2) Marsh gas mainly contains methane (3) Carbon black is obtaincd by hcating methanc in the abscnce of air (4) The simplest alkane that can be prepared by Wurtz reaction is methane

Short answer

Statement 4 is false.

Step-by-step solution

- Analyze Statement 1

Evaluate the statement: 'The name 'fire damp' is given to methane'. 'Fire damp' is indeed a term used for methane in coal mines. It is typically released during mining and can be explosive. This statement is true.

- Analyze Statement 2

Evaluate the statement: 'Marsh gas mainly contains methane'. Marsh gas, which forms in wetlands, is largely composed of methane due to anaerobic decomposition of organic matter. This statement is true.

- Analyze Statement 3

Evaluate the statement: 'Carbon black is obtained by heating methane in the absence of air'. Carbon black is indeed produced by burning hydrocarbons like methane in a limited supply of air (incomplete combustion). This statement is true.

- Analyze Statement 4

Evaluate the statement: 'The simplest alkane that can be prepared by Wurtz reaction is methane'. The Wurtz reaction involves coupling two alkyl halides to form a new carbon-carbon bond, typically yielding alkanes with at least two carbon atoms. Methane, having only one carbon atom, cannot be prepared via this reaction. This statement is false.

Key concepts

Fire Damp

Fire damp is a term used primarily in the context of coal mining. It refers to methane found within coal mines. Methane, a highly flammable gas, gets trapped in the coal seams. This poses significant danger due to its explosive nature when mixed with air. Methane can easily ignite, causing explosions with deadly consequences.
Coal miners refer to this trapped methane as 'fire damp' due to its explosive characteristic. Understanding how to manage and mitigate fire damp is critical in mining safety.
Fire damp monitoring systems are vital in modern mining operations to ensure safe working conditions.

Marsh Gas

Marsh gas is mainly composed of methane. It forms in wetlands due to anaerobic decomposition of organic matter.
This means that in the absence of oxygen, bacteria break down plant and animal material, producing methane as a byproduct. Wetlands, such as swamps and marshes, are ideal environments for this process.
Other gases like carbon dioxide and hydrogen sulfide can also be present but in much smaller quantities. The methane in marsh gas can sometimes be seen bubbling up to the surface of the water. This gas is not only a potent greenhouse gas but also a potential source of energy if captured and utilized correctly.

Carbon Black

Carbon black is a fine black powder produced by the incomplete combustion of hydrocarbons like methane. When methane burns with a limited supply of air, it doesn’t fully oxidize, resulting in the formation of carbon particles.
These particles aggregate and form carbon black, used extensively in various industries. Carbon black is a key ingredient in tire manufacturing, providing strength and durability to rubber.
Additionally, it’s used in printing inks, coatings, and plastics. The production and application of carbon black highlight the importance of controlled combustion processes in industrial chemistry.

Wurtz Reaction

The Wurtz reaction involves the coupling of two alkyl halides to form a new carbon-carbon bond, producing alkanes. It's named after the French chemist Charles Adolphe Wurtz.
In this reaction, the alkyl halides react with sodium metal, resulting in the formation of an alkane and sodium halide as byproducts. However, this reaction cannot produce methane, as methane has only one carbon atom and requires at least two carbon atoms for the coupling process.
The simplest alkane that can be prepared via the Wurtz reaction is ethane, which has two carbon atoms. This reaction demonstrates important principles in organic synthesis, particularly in forming longer carbon chains from smaller building blocks.