Methane (CH₄) is the simplest hydrocarbon and is the main component of natural gas. Describe what is meant by the term 'hydrocarbon' and explain why methane is described as a non-renewable fuel.

Eduqas A-Level Chemistry — 2.5 Hydrocarbons · Describe and Explain · 5 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Natural gas is widely used as a fuel in homes and power stations. It is extracted from underground reservoirs that formed over millions of years.

Model answer (5 marks)

A hydrocarbon is a compound that contains only hydrogen and carbon atoms.
Methane is a hydrocarbon.
Methane is a non‑renewable fuel because it is formed from the remains of dead organisms over millions of years.
Once it is extracted and used it cannot be replaced.
The rate at which methane is being used far exceeds the rate at which it can be formed.

Examiner tips

  • Use the exact definition of a hydrocarbon – hydrogen and carbon only. Explain non‑renewable in terms of formation time vs. consumption rate. Mention the origin of methane (dead organisms).

Common mistakes

  • Saying hydrocarbons contain oxygen or other elements. Claiming methane is renewable because it can be produced artificially. Failing to mention the millions‑year formation period.

Mark scheme (5 marks)

  1. A hydrocarbon contains hydrogen and carbon only
  2. Non-renewable means it cannot be replaced / replenished once used up
  3. Methane / natural gas was formed from the remains of dead organisms (plants/animals/marine organisms)
  4. It takes millions of years to form
  5. It is being used up much faster than it can be formed / rate of use exceeds rate of formation

Key terms in this question

hydrocarbon · non-renewable · natural gas · fuel

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