This exam tips covers Exam Tips: Combustion within Combustion for GCSE Chemistry. Revise Combustion in Organic Chemistry for GCSE Chemistry with 25 exam-style questions and 15 flashcards. Use this page as part of a wider topic revision path rather than treating it as an isolated fact. It is section 12 of 13 in this topic. Treat this as a marking guide for what examiners are looking for, not just a fact list.
Topic position
Section 12 of 13
Practice
25 questions
Recall
15 flashcards
💡 Exam Tips: Combustion
🎯 Common Question Types:
- Balance a combustion equation (2-3 marks)
- Compare complete and incomplete combustion (3-4 marks)
- Explain why CO is dangerous (2 marks)
- Suggest why a gas appliance has a yellow flame (1-2 marks)
📝 Key Command Words:
- Balance: Balance C, then H, then O. Check atom counts
- Compare: State differences in products, flame colour, energy
- Explain: Link CO to haemoglobin and oxygen transport
⚠️ Common Mistakes to Avoid:
- Forgetting soot/carbon as a possible product
- Saying ONLY CO₂ and H₂O are produced in incomplete combustion — incomplete combustion produces CO and/or carbon (soot) in addition to or instead of CO₂
- Forgetting state symbols in 6-mark questions
Quick Check: Write the balanced equation for the complete combustion of ethane (C₂H₆).
C₂H₆(g) + 3½O₂(g) → 2CO₂(g) + 3H₂O(l) OR: 2C₂H₆(g) + 7O₂(g) → 4CO₂(g) + 6H₂O(l). Step-by-step: 2 carbons → 2CO₂; 6 hydrogens → 3H₂O; oxygens needed = (2×2)+(3×1) = 7 → 3.5O₂ (or multiply through by 2).
Quick Check: A gas fire in a room with poor ventilation begins to produce a yellow flame. Suggest two risks this creates.
1. Carbon monoxide (CO) is produced — a colourless, odourless toxic gas that binds to haemoglobin and prevents oxygen transport, potentially causing death. 2. Soot/carbon particles are released into the air, causing respiratory problems and settling on surfaces.
Keep building this topic
Read this section alongside the surrounding pages in Combustion. That gives you the full topic sequence instead of a single isolated revision point.
Practice Questions for Combustion
What are the only products formed during the complete combustion of a hydrocarbon?
Explain why carbon monoxide (CO) is toxic to humans. [3 marks]
Quick Recall Flashcards
25 questions on Combustion — practise free
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