AQA GCSE · Question 05.2 · Chemistry of the atmosphere
Explain one positive impact on the environment of burning hydrogen rather than natural gas as a fuel. Use Table 2.
How to approach this question
1. Look at Table 2 and find a product that is environmentally damaging.
2. Compare the amount of this product produced by hydrogen versus natural gas.
3. Identify the case where hydrogen is "better" (produces less of a harmful substance).
4. State the harmful substance and explain *why* it is harmful to the environment.
Full Answer
By examining Table 2, we can compare the combustion products of hydrogen and natural gas.
- The row for "Mass of carbon dioxide produced" shows that burning 1 dm³ of hydrogen produces 0.00 g of CO₂, while natural gas produces 1.83 g.
- This is a significant positive impact because hydrogen fuel does not contain carbon atoms (it is just H₂), so it cannot produce carbon dioxide upon combustion. The only product is water (2H₂ + O₂ → 2H₂O).
- Carbon dioxide is a major greenhouse gas. It traps infrared radiation in the atmosphere, leading to an increase in the Earth's average temperature, known as global warming or climate change.
- Therefore, using hydrogen as a fuel instead of natural gas (which is mostly methane, CH₄) would eliminate these CO₂ emissions and help to mitigate climate change.
Common mistakes
✗ Just stating "it produces no carbon dioxide" without explaining the environmental consequence.
✗ Discussing other products like water or nitrogen oxides without focusing on a clear positive impact.
✗ Not using the data from the table to support the answer.
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