Balancing Chemical Equations

Name:

Date:

🎯 WALT & Success Criteria

We Are Learning To: Balance chemical equations for combustion and neutralisation reactions

Success Criteria - I can:

Explain why chemical equations must be balanced (conservation of mass)

Count atoms on both sides of an equation

Use coefficients to balance equations step by step

Balance combustion reactions (fuel + oxygen → carbon dioxide + water)

Balance neutralisation reactions (acid + base → salt + water)

📚 Part 1: Understanding Chemical Balance

1. Why must chemical equations be balanced? Choose the best answer.

To make them look neat and tidy

Because of the Law of Conservation of Mass

To make calculations easier

Because teachers say so

2. Count the atoms in this equation: 2H₂ + O₂ → 2H₂O

Left side: _____ hydrogen atoms, _____ oxygen atoms

Right side: _____ hydrogen atoms, _____ oxygen atoms

Is this equation balanced? _____

3. Which elements should you typically balance LAST in combustion reactions?

Carbon

Hydrogen

Oxygen

Metals

✏️ Part 2: Balancing Practice

4. Balance this combustion equation (methane burning):

_____ CH₄ + _____ O₂ → _____ CO₂ + _____ H₂O

5. Balance this neutralisation equation:

_____ HCl + _____ NaOH → _____ NaCl + _____ H₂O

6. Balance this more challenging combustion equation:

_____ C₂H₆ + _____ O₂ → _____ CO₂ + _____ H₂O

7. Extension Challenge: Balance this equation for propane combustion:

_____ C₃H₈ + _____ O₂ → _____ CO₂ + _____ H₂O

8. Explain in your own words why we can't change the chemical formulas (like H₂O) when balancing equations - we can only change the coefficients (the numbers in front).

9. Kitchen Chemistry Connection: When you burn natural gas (methane) on your stove, you're seeing the balanced equation from question 4. Describe what you observe when this reaction happens in your kitchen.