Question

A student wished to produce only carbon from the dioxide and water vapour combustion of methane, CH\(_4\). To accomplish this the student should

• A. burn CH\(_4\) in limited oxygen
• B. burn CH\(_4\) in a vacuum
• C. burn CH\(_4\) in excess oxygen
• D. burn CH\(_4\) at a very low temperature

Hint:

Excess oxygen ensures complete combustion and prevents the formation of incomplete combustion products like CO.

Answer 1

The Correct Option is C

To produce carbon, the combustion of methane should be carried out in excess oxygen. When methane (CH₄) undergoes complete combustion with excess oxygen, it forms carbon dioxide (CO₂) and water (H₂O). However, if there is insufficient oxygen, incomplete combustion may occur, leading to the formation of carbon monoxide (CO) or even elemental carbon (C). To ensure that carbon is produced during combustion, the reaction needs to be controlled, and typically, limiting oxygen in a controlled manner can yield carbon (as soot) rather than CO₂.

Therefore, to avoid the formation of CO₂ and produce carbon (soot), the combustion of methane must be done with limited oxygen, not excess oxygen.