Chapter 9 Balancing Equations - [email protected] - Free Printable
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Show Answer Key & Explanations
Step-by-step solution for: Chapter 9 Balancing Equations - [email protected]
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Show Answer Key & Explanations
Step-by-step solution for: Chapter 9 Balancing Equations - [email protected]
Let's solve each of these chemical equations by balancing them and identifying the type of reaction. I'll go step-by-step for each one.
---
Balancing:
- Left: 1 Ca, 2 O
- Right: 1 Ca, 1 O
We need 2 CaO to balance oxygen:
→ 2Ca + O₂ → 2CaO
✔ Balanced.
Type of Reaction: Combination (Synthesis) – two substances combine to form one product.
---
Check atoms:
- Left: Zn=1, S=1 (from ZnSO₄), S=1 (from (NH₄)₂S), N=2, H=8, O=4
- Right: N=2, H=8, S=1, O=4, Zn=1, S=1
All atoms are already balanced.
✔ Already balanced.
Type of Reaction: Double Replacement (Metathesis) – ions exchange partners.
---
Left: K=1, I=1, Cl=2
Right: K=1, Cl=1, I=2
Need to balance I and Cl.
- Use 2KI → gives 2K, 2I
- Cl₂ → 2Cl
- So 2KCl on right
- I₂ on right
→ 2KI + Cl₂ → 2KCl + I₂
✔ Balanced.
Type of Reaction: Single Replacement – Cl replaces I in KI.
---
This is combustion of propane.
Balance C first:
- 3C → 3CO₂
Balance H:
- 8H → 4H₂O
Now O:
- Right: 3×2 = 6 from CO₂, 4×1 = 4 from H₂O → total 10 O
- Left: O₂ → need 5 O₂
→ C₃H₈ + 5O₂ → 3CO₂ + 4H₂O
✔ Balanced.
Type of Reaction: Combustion
---
Left: C=1, H=2, O=1
Right: C=1, O=1, H=2
Already balanced.
✔ Balanced.
Type of Reaction: Single Replacement (or sometimes called a redox reaction)
---
Left: Ca=1, O=1+1=2, H=2
Right: Ca=1, O=2, H=2
Balanced.
✔ Balanced.
Type of Reaction: Combination (Synthesis)
---
Left: H=1+1=2, Cl=1, Na=1, O=1
Right: Na=1, Cl=1, H=2, O=1
Balanced.
✔ Balanced.
Type of Reaction: Acid-Base Neutralization (a type of double replacement)
---
Left: Ba=1, Cl=2, H=2, S=1, O=4
Right: Ba=1, S=1, O=4, H=1, Cl=1
Need 2HCl on right.
→ BaCl₂ + H₂SO₄ → BaSO₄ + 2HCl
✔ Balanced.
Type of Reaction: Double Replacement
---
Decomposition of aluminum oxide.
Left: Al=2, O=3
Right: Al=1, O=2
Balance Al: 2Al
Balance O: need 3/2 O₂ → better to use whole numbers.
Multiply entire equation by 2:
→ 2Al₂O₃ → 4Al + 3O₂
✔ Balanced.
Type of Reaction: Decomposition
---
Left: Al=1, H=1, Cl=1
Right: Al=1, Cl=3, H=2
Balance Cl: need 3HCl
Then H: 3H → so H₂ must be 3/2 → multiply by 2
→ 2Al + 6HCl → 2AlCl₃ + 3H₂
✔ Balanced.
Type of Reaction: Single Replacement
---
Left: Na=1, H=1, C=1, O=3
Right: Na=2, C=2, O=3+1+2=6, H=2
So we need 2NaHCO₃
→ 2NaHCO₃ → Na₂CO₃ + H₂O + CO₂
Check:
- Left: Na=2, H=2, C=2, O=6
- Right: Na=2, C=1+1=2, O=3+1+2=6, H=2
✔ Balanced.
Type of Reaction: Decomposition
---
Left: Mg=1, H=1, Cl=1
Right: H=2, Mg=1, Cl=2
Need 2HCl → gives 2H and 2Cl
→ Mg + 2HCl → H₂ + MgCl₂
✔ Balanced.
Type of Reaction: Single Replacement
---
Combustion of propene.
C₃H₆ → 3CO₂ (C balance)
H₆ → 3H₂O (H balance)
Now O:
- Right: 3×2 = 6 (CO₂) + 3×1 = 3 (H₂O) → total 9 O
- Left: O₂ → need 9/2 = 4.5 → multiply by 2
→ 2C₃H₆ + 9O₂ → 6CO₂ + 6H₂O
✔ Balanced.
Type of Reaction: Combustion
---
Left: Al=1, H=2, S=1, O=4
Right: Al=2, S=3, O=12, H=2
Balance Al: need 2Al
Balance SO₄: need 3H₂SO₄ → gives 6H, 3S, 12O
Then H₂: 6H → 3H₂
→ 2Al + 3H₂SO₄ → Al₂(SO₄)₃ + 3H₂
✔ Balanced.
Type of Reaction: Single Replacement
---
Left: Cu=1, O=1, H=2
Right: H=2, O=1, Cu=1
Balanced.
✔ Balanced.
Type of Reaction: Single Replacement (Reduction of metal oxide)
---
Nitrogen and hydrogen make ammonia.
N₂ → 2NH₃ → needs 3H₂
→ N₂ + 3H₂ → 2NH₃
✔ Balanced.
Type of Reaction: Combination (Synthesis)
---
This is a disproportionation reaction.
Left: Cl=2, K=1, O=1, H=1
Right: K=1+1=2, Cl=1+1=2, O=1, H=2
So need 2KOH
→ Cl₂ + 2KOH → KCl + KClO + H₂O
Check:
- Left: Cl=2, K=2, O=2, H=2
- Right: K=1+1=2, Cl=1+1=2, O=1+1=2, H=2
✔ Balanced.
Type of Reaction: Disproportionation (a type of redox)
---
Combustion of ethane.
C₂H₆ → 2CO₂
H₆ → 3H₂O
O:
- Right: 2×2 = 4 (CO₂) + 3×1 = 3 (H₂O) → 7 O
- Left: O₂ → 7/2 → multiply by 2
→ 2C₂H₆ + 7O₂ → 4CO₂ + 6H₂O
✔ Balanced.
Type of Reaction: Combustion
---
Butane combustion.
C₄H₁₀ → 4CO₂
H₁₀ → 5H₂O
O:
- Right: 4×2 = 8 + 5×1 = 5 → 13 O
- Left: O₂ → 13/2 → multiply by 2
→ 2C₄H₁₀ + 13O₂ → 8CO₂ + 10H₂O
✔ Balanced.
Type of Reaction: Combustion
---
Left: Bi=1, N=3, O=9, H=2, S=1
Right: Bi=2, S=3, H=1, N=1, O=3
Need 2Bi(NO₃)₃ → Bi=2, N=6, O=18, H=2, S=1 → but need 3S → 3H₂S
→ 3H₂S → H=6, S=3
Then HNO₃: 6HNO₃ → H=6, N=6, O=18
Now check:
Left:
- 2Bi(NO₃)₃: Bi=2, N=6, O=18
- 3H₂S: H=6, S=3
Right:
- Bi₂S₃: Bi=2, S=3
- 6HNO₃: H=6, N=6, O=18
✔ Balanced.
→ 2Bi(NO₃)₃ + 3H₂S → Bi₂S₃ + 6HNO₃
Type of Reaction: Double Replacement
---
## ✔ Final Answers:
| # | Balanced Equation | Type of Reaction |
|---|-------------------|------------------|
| 1 | 2Ca + O₂ → 2CaO | Combination |
| 2 | ZnSO₄ + (NH₄)₂S → (NH₄)₂SO₄ + ZnS | Double Replacement |
| 3 | 2KI + Cl₂ → 2KCl + I₂ | Single Replacement |
| 4 | C₃H₈ + 5O₂ → 3CO₂ + 4H₂O | Combustion |
| 5 | C + H₂O → CO + H₂ | Single Replacement |
| 6 | CaO + H₂O → Ca(OH)₂ | Combination |
| 7 | HCl + NaOH → NaCl + H₂O | Acid-Base Neutralization |
| 8 | BaCl₂ + H₂SO₄ → BaSO₄ + 2HCl | Double Replacement |
| 9 | 2Al₂O₃ → 4Al + 3O₂ | Decomposition |
| 10 | 2Al + 6HCl → 2AlCl₃ + 3H₂ | Single Replacement |
| 11 | 2NaHCO₃ → Na₂CO₃ + H₂O + CO₂ | Decomposition |
| 12 | Mg + 2HCl → H₂ + MgCl₂ | Single Replacement |
| 13 | 2C₃H₆ + 9O₂ → 6CO₂ + 6H₂O | Combustion |
| 14 | 2Al + 3H₂SO₄ → Al₂(SO₄)₃ + 3H₂ | Single Replacement |
| 15 | CuO + H₂ → H₂O + Cu | Single Replacement |
| 16 | N₂ + 3H₂ → 2NH₃ | Combination |
| 17 | Cl₂ + 2KOH → KCl + KClO + H₂O | Disproportionation |
| 18 | 2C₂H₆ + 7O₂ → 4CO₂ + 6H₂O | Combustion |
| 19 | 2C₄H₁₀ + 13O₂ → 8CO₂ + 10H₂O | Combustion |
| 20 | 2Bi(NO₃)₃ + 3H₂S → Bi₂S₃ + 6HNO₃ | Double Replacement |
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---
1. Ca + O₂ → CaO
Balancing:
- Left: 1 Ca, 2 O
- Right: 1 Ca, 1 O
We need 2 CaO to balance oxygen:
→ 2Ca + O₂ → 2CaO
✔ Balanced.
Type of Reaction: Combination (Synthesis) – two substances combine to form one product.
---
2. ZnSO₄ + (NH₄)₂S → (NH₄)₂SO₄ + ZnS
Check atoms:
- Left: Zn=1, S=1 (from ZnSO₄), S=1 (from (NH₄)₂S), N=2, H=8, O=4
- Right: N=2, H=8, S=1, O=4, Zn=1, S=1
All atoms are already balanced.
✔ Already balanced.
Type of Reaction: Double Replacement (Metathesis) – ions exchange partners.
---
3. KI + Cl₂ → KCl + I₂
Left: K=1, I=1, Cl=2
Right: K=1, Cl=1, I=2
Need to balance I and Cl.
- Use 2KI → gives 2K, 2I
- Cl₂ → 2Cl
- So 2KCl on right
- I₂ on right
→ 2KI + Cl₂ → 2KCl + I₂
✔ Balanced.
Type of Reaction: Single Replacement – Cl replaces I in KI.
---
4. C₃H₈ + O₂ → CO₂ + H₂O
This is combustion of propane.
Balance C first:
- 3C → 3CO₂
Balance H:
- 8H → 4H₂O
Now O:
- Right: 3×2 = 6 from CO₂, 4×1 = 4 from H₂O → total 10 O
- Left: O₂ → need 5 O₂
→ C₃H₈ + 5O₂ → 3CO₂ + 4H₂O
✔ Balanced.
Type of Reaction: Combustion
---
5. C + H₂O → CO + H₂
Left: C=1, H=2, O=1
Right: C=1, O=1, H=2
Already balanced.
✔ Balanced.
Type of Reaction: Single Replacement (or sometimes called a redox reaction)
---
6. CaO + H₂O → Ca(OH)₂
Left: Ca=1, O=1+1=2, H=2
Right: Ca=1, O=2, H=2
Balanced.
✔ Balanced.
Type of Reaction: Combination (Synthesis)
---
7. HCl + NaOH → NaCl + H₂O
Left: H=1+1=2, Cl=1, Na=1, O=1
Right: Na=1, Cl=1, H=2, O=1
Balanced.
✔ Balanced.
Type of Reaction: Acid-Base Neutralization (a type of double replacement)
---
8. BaCl₂ + H₂SO₄ → BaSO₄ + HCl
Left: Ba=1, Cl=2, H=2, S=1, O=4
Right: Ba=1, S=1, O=4, H=1, Cl=1
Need 2HCl on right.
→ BaCl₂ + H₂SO₄ → BaSO₄ + 2HCl
✔ Balanced.
Type of Reaction: Double Replacement
---
9. Al₂O₃ → Al + O₂
Decomposition of aluminum oxide.
Left: Al=2, O=3
Right: Al=1, O=2
Balance Al: 2Al
Balance O: need 3/2 O₂ → better to use whole numbers.
Multiply entire equation by 2:
→ 2Al₂O₃ → 4Al + 3O₂
✔ Balanced.
Type of Reaction: Decomposition
---
10. Al + HCl → AlCl₃ + H₂
Left: Al=1, H=1, Cl=1
Right: Al=1, Cl=3, H=2
Balance Cl: need 3HCl
Then H: 3H → so H₂ must be 3/2 → multiply by 2
→ 2Al + 6HCl → 2AlCl₃ + 3H₂
✔ Balanced.
Type of Reaction: Single Replacement
---
11. NaHCO₃ → Na₂CO₃ + H₂O + CO₂
Left: Na=1, H=1, C=1, O=3
Right: Na=2, C=2, O=3+1+2=6, H=2
So we need 2NaHCO₃
→ 2NaHCO₃ → Na₂CO₃ + H₂O + CO₂
Check:
- Left: Na=2, H=2, C=2, O=6
- Right: Na=2, C=1+1=2, O=3+1+2=6, H=2
✔ Balanced.
Type of Reaction: Decomposition
---
12. Mg + HCl → H₂ + MgCl₂
Left: Mg=1, H=1, Cl=1
Right: H=2, Mg=1, Cl=2
Need 2HCl → gives 2H and 2Cl
→ Mg + 2HCl → H₂ + MgCl₂
✔ Balanced.
Type of Reaction: Single Replacement
---
13. C₃H₆ + O₂ → CO₂ + H₂O
Combustion of propene.
C₃H₆ → 3CO₂ (C balance)
H₆ → 3H₂O (H balance)
Now O:
- Right: 3×2 = 6 (CO₂) + 3×1 = 3 (H₂O) → total 9 O
- Left: O₂ → need 9/2 = 4.5 → multiply by 2
→ 2C₃H₆ + 9O₂ → 6CO₂ + 6H₂O
✔ Balanced.
Type of Reaction: Combustion
---
14. Al + H₂SO₄ → Al₂(SO₄)₃ + H₂
Left: Al=1, H=2, S=1, O=4
Right: Al=2, S=3, O=12, H=2
Balance Al: need 2Al
Balance SO₄: need 3H₂SO₄ → gives 6H, 3S, 12O
Then H₂: 6H → 3H₂
→ 2Al + 3H₂SO₄ → Al₂(SO₄)₃ + 3H₂
✔ Balanced.
Type of Reaction: Single Replacement
---
15. CuO + H₂ → H₂O + Cu
Left: Cu=1, O=1, H=2
Right: H=2, O=1, Cu=1
Balanced.
✔ Balanced.
Type of Reaction: Single Replacement (Reduction of metal oxide)
---
16. N₂ + H₂ → NH₃
Nitrogen and hydrogen make ammonia.
N₂ → 2NH₃ → needs 3H₂
→ N₂ + 3H₂ → 2NH₃
✔ Balanced.
Type of Reaction: Combination (Synthesis)
---
17. Cl₂ + KOH → KCl + KClO + H₂O
This is a disproportionation reaction.
Left: Cl=2, K=1, O=1, H=1
Right: K=1+1=2, Cl=1+1=2, O=1, H=2
So need 2KOH
→ Cl₂ + 2KOH → KCl + KClO + H₂O
Check:
- Left: Cl=2, K=2, O=2, H=2
- Right: K=1+1=2, Cl=1+1=2, O=1+1=2, H=2
✔ Balanced.
Type of Reaction: Disproportionation (a type of redox)
---
18. C₂H₆ + O₂ → CO₂ + H₂O
Combustion of ethane.
C₂H₆ → 2CO₂
H₆ → 3H₂O
O:
- Right: 2×2 = 4 (CO₂) + 3×1 = 3 (H₂O) → 7 O
- Left: O₂ → 7/2 → multiply by 2
→ 2C₂H₆ + 7O₂ → 4CO₂ + 6H₂O
✔ Balanced.
Type of Reaction: Combustion
---
19. C₄H₁₀ + O₂ → CO₂ + H₂O
Butane combustion.
C₄H₁₀ → 4CO₂
H₁₀ → 5H₂O
O:
- Right: 4×2 = 8 + 5×1 = 5 → 13 O
- Left: O₂ → 13/2 → multiply by 2
→ 2C₄H₁₀ + 13O₂ → 8CO₂ + 10H₂O
✔ Balanced.
Type of Reaction: Combustion
---
20. Bi(NO₃)₃ + H₂S → Bi₂S₃ + HNO₃
Left: Bi=1, N=3, O=9, H=2, S=1
Right: Bi=2, S=3, H=1, N=1, O=3
Need 2Bi(NO₃)₃ → Bi=2, N=6, O=18, H=2, S=1 → but need 3S → 3H₂S
→ 3H₂S → H=6, S=3
Then HNO₃: 6HNO₃ → H=6, N=6, O=18
Now check:
Left:
- 2Bi(NO₃)₃: Bi=2, N=6, O=18
- 3H₂S: H=6, S=3
Right:
- Bi₂S₃: Bi=2, S=3
- 6HNO₃: H=6, N=6, O=18
✔ Balanced.
→ 2Bi(NO₃)₃ + 3H₂S → Bi₂S₃ + 6HNO₃
Type of Reaction: Double Replacement
---
## ✔ Final Answers:
| # | Balanced Equation | Type of Reaction |
|---|-------------------|------------------|
| 1 | 2Ca + O₂ → 2CaO | Combination |
| 2 | ZnSO₄ + (NH₄)₂S → (NH₄)₂SO₄ + ZnS | Double Replacement |
| 3 | 2KI + Cl₂ → 2KCl + I₂ | Single Replacement |
| 4 | C₃H₈ + 5O₂ → 3CO₂ + 4H₂O | Combustion |
| 5 | C + H₂O → CO + H₂ | Single Replacement |
| 6 | CaO + H₂O → Ca(OH)₂ | Combination |
| 7 | HCl + NaOH → NaCl + H₂O | Acid-Base Neutralization |
| 8 | BaCl₂ + H₂SO₄ → BaSO₄ + 2HCl | Double Replacement |
| 9 | 2Al₂O₃ → 4Al + 3O₂ | Decomposition |
| 10 | 2Al + 6HCl → 2AlCl₃ + 3H₂ | Single Replacement |
| 11 | 2NaHCO₃ → Na₂CO₃ + H₂O + CO₂ | Decomposition |
| 12 | Mg + 2HCl → H₂ + MgCl₂ | Single Replacement |
| 13 | 2C₃H₆ + 9O₂ → 6CO₂ + 6H₂O | Combustion |
| 14 | 2Al + 3H₂SO₄ → Al₂(SO₄)₃ + 3H₂ | Single Replacement |
| 15 | CuO + H₂ → H₂O + Cu | Single Replacement |
| 16 | N₂ + 3H₂ → 2NH₃ | Combination |
| 17 | Cl₂ + 2KOH → KCl + KClO + H₂O | Disproportionation |
| 18 | 2C₂H₆ + 7O₂ → 4CO₂ + 6H₂O | Combustion |
| 19 | 2C₄H₁₀ + 13O₂ → 8CO₂ + 10H₂O | Combustion |
| 20 | 2Bi(NO₃)₃ + 3H₂S → Bi₂S₃ + 6HNO₃ | Double Replacement |
Let me know if you'd like this formatted as a printable sheet!
Parent Tip: Review the logic above to help your child master the concept of chapter 7 worksheet 1 balancing chemical equations.
![49 Balancing Chemical Equations Worksheets [with Answers]](/images2/chapter-7-worksheet-1-balancing-chemical-equations/chapter-7-worksheet-1-balancing-chemical-equations-24.jpg)
