Combustion: Reactions, Atoms & Real-World Impacts

Combustion: Reactions, Atoms & Real-World Impacts

Understanding chemical reactions that power our world Year 11 Chemistry Duration: 15 minutes

Do Now: Quick Fire Questions (10 minutes)

1. What are the two main products of complete combustion? 2. Balance: CH₄ + O₂ → CO₂ + H₂O 3. How many carbon atoms are in C₃H₈? 4. Name one environmental concern from incomplete combustion 5. What gas is produced during incomplete combustion? 6. Calculate atoms in 2CO₂ molecules 7. Why is carbon monoxide dangerous? 8. Give an example of combustion in everyday life 9. What does the Law of Conservation of Mass state? 10. Complete: C₂H₆ + O₂ → ? + ?

What is Combustion?

A chemical reaction between a fuel and oxygen Releases energy in the form of heat and light Fuel + Oxygen → Products + Energy Examples: burning wood, gas stoves, car engines

Complete vs Incomplete Combustion

{"left":"Complete Combustion\nSufficient oxygen supply\nProduces CO₂ and H₂O\nClean blue flame\nMore efficient energy release","right":"Incomplete Combustion\nLimited oxygen supply\nProduces CO, C, and H₂O\nYellow/orange flame with soot\nLess efficient, produces pollutants"}

Counting Atoms in Chemical Equations

Atoms are neither created nor destroyed Count each type of atom on both sides Use coefficients to balance equations Example: CH₄ + 2O₂ → CO₂ + 2H₂O

Law of Conservation of Mass

"In a chemical reaction, mass is neither created nor destroyed - it is conserved." - Antoine Lavoisier This means the total mass of reactants equals the total mass of products

Balancing Practice

Work with a partner to balance these equations: C₃H₈ + O₂ → CO₂ + H₂O C₂H₆ + O₂ → CO₂ + H₂O C₄H₁₀ + O₂ → CO₂ + H₂O Check your atom counts! Remember: coefficients go in front of formulas

Real-World Applications of Combustion

Environmental and Health Impacts

Carbon monoxide (CO) - toxic, odorless gas Carbon dioxide (CO₂) - greenhouse gas contributing to climate change Particulate matter (soot) - respiratory problems Nitrogen oxides - acid rain and smog Importance of proper ventilation and emission controls

Think-Pair-Share

Why might a car produce more pollution in stop-and-go traffic compared to highway driving? Consider: Oxygen supply to the engine Combustion efficiency Engine temperature

Summary: Key Takeaways

Combustion requires fuel, oxygen, and produces energy Complete combustion: CO₂ + H₂O (efficient, cleaner) Incomplete combustion: CO + C + H₂O (inefficient, polluting) Law of Conservation of Mass governs all reactions Balancing equations ensures atom conservation Real-world impacts on health and environment