This worked example covers Worked Example: CO₂ from Fuel Combustion within Climate Change for GCSE Chemistry. Revise Climate Change in Atmosphere for GCSE Chemistry with 20 exam-style questions and 15 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 10 of 17 in this topic. Treat this as a marking guide for what examiners are looking for, not just a fact list.
🧮 Worked Example: CO₂ from Fuel Combustion
Question: Calculate the mass of CO₂ produced when 1 kg of octane (C₈H₁₈) burns completely.
Solution:
- Balanced equation: 2C₈H₁₈ + 25O₂ → 16CO₂ + 18H₂O
- Molar masses: Mr(C₈H₁₈) = (8 × 12) + (18 × 1) = 114 g/mol; Mr(CO₂) = 12 + (2 × 16) = 44 g/mol
- Mole ratio: 2 mol C₈H₁₈ → 16 mol CO₂; so 1 mol C₈H₁₈ → 8 mol CO₂
- Mass ratio: 114 g C₈H₁₈ → 8 × 44 = 352 g CO₂
- For 1 kg (1000 g): CO₂ = (1000 ÷ 114) × 352 = 3090 g = 3.09 kg
Answer: 1 kg of octane produces about 3.09 kg of CO₂ — showing why transport is such a large contributor to emissions.
Practice questions for Climate Change
Which statement correctly describes the difference between weather and climate?
Explain three consequences of climate change for the environment or human populations. [3 marks]