Combustion Reaction Worksheet | PDF | Hydrocarbons | Propane - Free Printable
Educational worksheet: Combustion Reaction Worksheet | PDF | Hydrocarbons | Propane. Download and print for classroom or home learning activities.
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Step-by-step solution for: Combustion Reaction Worksheet | PDF | Hydrocarbons | Propane
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Show Answer Key & Explanations
Step-by-step solution for: Combustion Reaction Worksheet | PDF | Hydrocarbons | Propane
You're working on Worksheet #6: Combustion Reactions, which focuses on the complete combustion of hydrocarbons. In a complete combustion reaction, a hydrocarbon reacts with oxygen (O₂) to produce carbon dioxide (CO₂) and water (H₂O).
The general form is:
> Hydrocarbon + O₂ → CO₂ + H₂O
We must balance each equation so that the number of atoms of each element is equal on both sides.
---
Let’s solve each one step by step:
---
Unbalanced:
CH₄ + O₂ → CO₂ + H₂O
Balance C: 1 C on left → 1 CO₂ on right → OK
Balance H: 4 H on left → need 2 H₂O on right (since each H₂O has 2 H)
→ CH₄ + O₂ → CO₂ + 2H₂O
Balance O: Right side has 2 (from CO₂) + 2×1 = 4 O from 2H₂O → total 4 O atoms
Left: O₂ → need 2 O₂ molecules → 4 O atoms
✔ Balanced Equation:
CH₄ + 2O₂ → CO₂ + 2H₂O
---
Unbalanced:
C₂H₆ + O₂ → CO₂ + H₂O
Balance C: 2 C → 2 CO₂
Balance H: 6 H → 3 H₂O (since 3×2=6 H)
→ C₂H₆ + O₂ → 2CO₂ + 3H₂O
Balance O: Right: 2×2 = 4 from CO₂ + 3×1 = 3 from H₂O → total 7 O atoms
Left: O₂ → need 7/2 O₂ → multiply entire equation by 2 to eliminate fraction.
Multiply all by 2:
2C₂H₆ + 7O₂ → 4CO₂ + 6H₂O
✔ Balanced Equation:
2C₂H₆ + 7O₂ → 4CO₂ + 6H₂O
---
Unbalanced:
C₃H₈ + O₂ → CO₂ + H₂O
Balance C: 3 → 3CO₂
Balance H: 8 H → 4H₂O
→ C₃H₈ + O₂ → 3CO₂ + 4H₂O
Balance O: Right: 3×2 = 6 from CO₂ + 4×1 = 4 from H₂O → total 10 O
Left: O₂ → need 5 O₂
✔ Balanced Equation:
C₃H₈ + 5O₂ → 3CO₂ + 4H₂O
---
Unbalanced:
C₄H₁₀ + O₂ → CO₂ + H₂O
Balance C: 4 → 4CO₂
Balance H: 10 H → 5H₂O
→ C₄H₁₀ + O₂ → 4CO₂ + 5H₂O
Balance O: Right: 4×2 = 8 from CO₂ + 5×1 = 5 from H₂O → total 13 O
Left: O₂ → need 13/2 O₂ → multiply entire equation by 2.
2C₄H₁₀ + 13O₂ → 8CO₂ + 10H₂O
✔ Balanced Equation:
2C₄H₁₀ + 13O₂ → 8CO₂ + 10H₂O
---
Unbalanced:
C₅H₁₂ + O₂ → CO₂ + H₂O
Balance C: 5 → 5CO₂
Balance H: 12 H → 6H₂O
→ C₅H₁₂ + O₂ → 5CO₂ + 6H₂O
Balance O: Right: 5×2 = 10 from CO₂ + 6×1 = 6 from H₂O → total 16 O
Left: O₂ → need 8 O₂
✔ Balanced Equation:
C₅H₁₂ + 8O₂ → 5CO₂ + 6H₂O
---
Unbalanced:
C₆H₁₄ + O₂ → CO₂ + H₂O
Balance C: 6 → 6CO₂
Balance H: 14 H → 7H₂O
→ C₆H₁₄ + O₂ → 6CO₂ + 7H₂O
Balance O: Right: 6×2 = 12 from CO₂ + 7×1 = 7 from H₂O → total 19 O
Left: O₂ → need 19/2 O₂ → multiply entire equation by 2.
2C₆H₁₄ + 19O₂ → 12CO₂ + 14H₂O
✔ Balanced Equation:
2C₆H₁₄ + 19O₂ → 12CO₂ + 14H₂O
---
Unbalanced:
C₂H₄ + O₂ → CO₂ + H₂O
Balance C: 2 → 2CO₂
Balance H: 4 H → 2H₂O
→ C₂H₄ + O₂ → 2CO₂ + 2H₂O
Balance O: Right: 2×2 = 4 from CO₂ + 2×1 = 2 from H₂O → total 6 O
Left: O₂ → need 3 O₂
✔ Balanced Equation:
C₂H₄ + 3O₂ → 2CO₂ + 2H₂O
---
Unbalanced:
C₂H₂ + O₂ → CO₂ + H₂O
Balance C: 2 → 2CO₂
Balance H: 2 H → 1H₂O
→ C₂H₂ + O₂ → 2CO₂ + H₂O
Balance O: Right: 2×2 = 4 from CO₂ + 1×1 = 1 from H₂O → total 5 O
Left: O₂ → need 5/2 O₂ → multiply entire equation by 2.
2C₂H₂ + 5O₂ → 4CO₂ + 2H₂O
✔ Balanced Equation:
2C₂H₂ + 5O₂ → 4CO₂ + 2H₂O
---
Unbalanced:
C₆H₆ + O₂ → CO₂ + H₂O
Balance C: 6 → 6CO₂
Balance H: 6 H → 3H₂O
→ C₆H₆ + O₂ → 6CO₂ + 3H₂O
Balance O: Right: 6×2 = 12 from CO₂ + 3×1 = 3 from H₂O → total 15 O
Left: O₂ → need 15/2 O₂ → multiply entire equation by 2.
2C₆H₆ + 15O₂ → 12CO₂ + 6H₂O
✔ Balanced Equation:
2C₆H₆ + 15O₂ → 12CO₂ + 6H₂O
---
## ✔ Final Answers:
1. CH₄ + 2O₂ → CO₂ + 2H₂O
2. 2C₂H₆ + 7O₂ → 4CO₂ + 6H₂O
3. C₃H₈ + 5O₂ → 3CO₂ + 4H₂O
4. 2C₄H₁₀ + 13O₂ → 8CO₂ + 10H₂O
5. C₅H₁₂ + 8O₂ → 5CO₂ + 6H₂O
6. 2C₆H₁₄ + 19O₂ → 12CO₂ + 14H₂O
7. C₂H₄ + 3O₂ → 2CO₂ + 2H₂O
8. 2C₂H₂ + 5O₂ → 4CO₂ + 2H₂O
9. 2C₆H₆ + 15O₂ → 12CO₂ + 6H₂O
---
## 💡 Tip for Balancing Combustion Reactions:
- Balance Carbon (C) first → CO₂
- Then Hydrogen (H) → H₂O
- Finally Oxygen (O) — count total O on right, then adjust O₂ on left.
- If you get a fraction for O₂, multiply the whole equation by 2 to eliminate it.
Let me know if you’d like to practice incomplete combustion or learn about energy released too!
The general form is:
> Hydrocarbon + O₂ → CO₂ + H₂O
We must balance each equation so that the number of atoms of each element is equal on both sides.
---
Let’s solve each one step by step:
---
1. Methane (CH₄) + Oxygen → ?
Unbalanced:
CH₄ + O₂ → CO₂ + H₂O
Balance C: 1 C on left → 1 CO₂ on right → OK
Balance H: 4 H on left → need 2 H₂O on right (since each H₂O has 2 H)
→ CH₄ + O₂ → CO₂ + 2H₂O
Balance O: Right side has 2 (from CO₂) + 2×1 = 4 O from 2H₂O → total 4 O atoms
Left: O₂ → need 2 O₂ molecules → 4 O atoms
✔ Balanced Equation:
CH₄ + 2O₂ → CO₂ + 2H₂O
---
2. Ethane (C₂H₆) + Oxygen → ?
Unbalanced:
C₂H₆ + O₂ → CO₂ + H₂O
Balance C: 2 C → 2 CO₂
Balance H: 6 H → 3 H₂O (since 3×2=6 H)
→ C₂H₆ + O₂ → 2CO₂ + 3H₂O
Balance O: Right: 2×2 = 4 from CO₂ + 3×1 = 3 from H₂O → total 7 O atoms
Left: O₂ → need 7/2 O₂ → multiply entire equation by 2 to eliminate fraction.
Multiply all by 2:
2C₂H₆ + 7O₂ → 4CO₂ + 6H₂O
✔ Balanced Equation:
2C₂H₆ + 7O₂ → 4CO₂ + 6H₂O
---
3. Propane (C₃H₈) + Oxygen → ?
Unbalanced:
C₃H₈ + O₂ → CO₂ + H₂O
Balance C: 3 → 3CO₂
Balance H: 8 H → 4H₂O
→ C₃H₈ + O₂ → 3CO₂ + 4H₂O
Balance O: Right: 3×2 = 6 from CO₂ + 4×1 = 4 from H₂O → total 10 O
Left: O₂ → need 5 O₂
✔ Balanced Equation:
C₃H₈ + 5O₂ → 3CO₂ + 4H₂O
---
4. Butane (C₄H₁₀) + Oxygen → ?
Unbalanced:
C₄H₁₀ + O₂ → CO₂ + H₂O
Balance C: 4 → 4CO₂
Balance H: 10 H → 5H₂O
→ C₄H₁₀ + O₂ → 4CO₂ + 5H₂O
Balance O: Right: 4×2 = 8 from CO₂ + 5×1 = 5 from H₂O → total 13 O
Left: O₂ → need 13/2 O₂ → multiply entire equation by 2.
2C₄H₁₀ + 13O₂ → 8CO₂ + 10H₂O
✔ Balanced Equation:
2C₄H₁₀ + 13O₂ → 8CO₂ + 10H₂O
---
5. Pentane (C₅H₁₂) + Oxygen → ?
Unbalanced:
C₅H₁₂ + O₂ → CO₂ + H₂O
Balance C: 5 → 5CO₂
Balance H: 12 H → 6H₂O
→ C₅H₁₂ + O₂ → 5CO₂ + 6H₂O
Balance O: Right: 5×2 = 10 from CO₂ + 6×1 = 6 from H₂O → total 16 O
Left: O₂ → need 8 O₂
✔ Balanced Equation:
C₅H₁₂ + 8O₂ → 5CO₂ + 6H₂O
---
6. Hexane (C₆H₁₄) + Oxygen → ?
Unbalanced:
C₆H₁₄ + O₂ → CO₂ + H₂O
Balance C: 6 → 6CO₂
Balance H: 14 H → 7H₂O
→ C₆H₁₄ + O₂ → 6CO₂ + 7H₂O
Balance O: Right: 6×2 = 12 from CO₂ + 7×1 = 7 from H₂O → total 19 O
Left: O₂ → need 19/2 O₂ → multiply entire equation by 2.
2C₆H₁₄ + 19O₂ → 12CO₂ + 14H₂O
✔ Balanced Equation:
2C₆H₁₄ + 19O₂ → 12CO₂ + 14H₂O
---
7. Ethene (C₂H₄) + Oxygen → ?
Unbalanced:
C₂H₄ + O₂ → CO₂ + H₂O
Balance C: 2 → 2CO₂
Balance H: 4 H → 2H₂O
→ C₂H₄ + O₂ → 2CO₂ + 2H₂O
Balance O: Right: 2×2 = 4 from CO₂ + 2×1 = 2 from H₂O → total 6 O
Left: O₂ → need 3 O₂
✔ Balanced Equation:
C₂H₄ + 3O₂ → 2CO₂ + 2H₂O
---
8. Ethyne (C₂H₂) + Oxygen → ?
Unbalanced:
C₂H₂ + O₂ → CO₂ + H₂O
Balance C: 2 → 2CO₂
Balance H: 2 H → 1H₂O
→ C₂H₂ + O₂ → 2CO₂ + H₂O
Balance O: Right: 2×2 = 4 from CO₂ + 1×1 = 1 from H₂O → total 5 O
Left: O₂ → need 5/2 O₂ → multiply entire equation by 2.
2C₂H₂ + 5O₂ → 4CO₂ + 2H₂O
✔ Balanced Equation:
2C₂H₂ + 5O₂ → 4CO₂ + 2H₂O
---
9. Benzene (C₆H₆) + Oxygen → ?
Unbalanced:
C₆H₆ + O₂ → CO₂ + H₂O
Balance C: 6 → 6CO₂
Balance H: 6 H → 3H₂O
→ C₆H₆ + O₂ → 6CO₂ + 3H₂O
Balance O: Right: 6×2 = 12 from CO₂ + 3×1 = 3 from H₂O → total 15 O
Left: O₂ → need 15/2 O₂ → multiply entire equation by 2.
2C₆H₆ + 15O₂ → 12CO₂ + 6H₂O
✔ Balanced Equation:
2C₆H₆ + 15O₂ → 12CO₂ + 6H₂O
---
## ✔ Final Answers:
1. CH₄ + 2O₂ → CO₂ + 2H₂O
2. 2C₂H₆ + 7O₂ → 4CO₂ + 6H₂O
3. C₃H₈ + 5O₂ → 3CO₂ + 4H₂O
4. 2C₄H₁₀ + 13O₂ → 8CO₂ + 10H₂O
5. C₅H₁₂ + 8O₂ → 5CO₂ + 6H₂O
6. 2C₆H₁₄ + 19O₂ → 12CO₂ + 14H₂O
7. C₂H₄ + 3O₂ → 2CO₂ + 2H₂O
8. 2C₂H₂ + 5O₂ → 4CO₂ + 2H₂O
9. 2C₆H₆ + 15O₂ → 12CO₂ + 6H₂O
---
## 💡 Tip for Balancing Combustion Reactions:
- Balance Carbon (C) first → CO₂
- Then Hydrogen (H) → H₂O
- Finally Oxygen (O) — count total O on right, then adjust O₂ on left.
- If you get a fraction for O₂, multiply the whole equation by 2 to eliminate it.
Let me know if you’d like to practice incomplete combustion or learn about energy released too!
Parent Tip: Review the logic above to help your child master the concept of combustion reaction worksheet.
