Key ideas1 of 3
Start with the products
For complete combustion, write the hydrocarbon and O₂ on the left; write CO₂ and H₂O on the right. Count atoms on each side. Only change the large coefficients, never the small subscripts.
![C₃H₈ + O₂ → CO₂ + H₂O. Atom counts on the left and right: [(3, 1), (8, 2), (2, 3)]](assets/organic/balance-0.svg)
Chemistry · Paper 2 · Foundation + Higher · C7
Balance combustion equations
No timer. Read the explanation after each answer.
Lesson questions complete
Practice, downloads and sources
Daily 5 · Exam practice · Revision sheet ↓
Foundation + Higher · C7. All C7 lessons are shared by Foundation and Higher Tier.
AQA Combined Science Trilogy 8464 · 5.7.1.3. Original notes, questions and diagrams. Models are simplified, not to scale; illustrative data are labelled.