Balancing Equations Worksheet featuring 22 chemical reactions for practice in balancing equations.
Balancing Equations Worksheet with 22 chemical equations to balance, including reactants and products.
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Step-by-step solution for: Predicting Products And Balancing Equations Worksheet Answers ...
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Show Answer Key & Explanations
Step-by-step solution for: Predicting Products And Balancing Equations Worksheet Answers ...
Let's go through each of the 22 chemical equations and balance them step by step. The goal is to ensure that the number of atoms of each element is the same on both sides of the equation (conservation of mass). We'll use coefficients (whole numbers placed in front of formulas) to balance.
---
- Left: Ca = 1, O = 2
- Right: Ca = 1, O = 1 → Not balanced
- Balance O: Need 2 CaO on right → 2 CaO → now need 2 Ca on left
- Answer:
2Ca + O₂ → 2CaO
---
- Left: H = 2, Cl = 2
- Right: H = 1, Cl = 1 → Need 2 HCl
- Answer:
H₂ + Cl₂ → 2HCl
---
- Left: P = 4, S = 8
- Right: P = 2, S = 5 → LCM for P and S needed
- Target: Make P = 4, S = 10? But S₈ has 8 S → try to match.
- Use 2P₂S₅ → P = 4, S = 10 → but S₈ has 8 S → not divisible
- Try 4P₂S₅ → P = 8, S = 20 → need P₄ × 2 = 8 P, S₈ × 2.5 → not integer
- Try P₄ + 5/4 S₈ → 2P₂S₅ → multiply all by 4:
- 4P₄ + 5S₈ → 8P₂S₅ → check:
- P: 16 = 16 ✔
- S: 40 = 40 ✔
- Answer:
4P₄ + 5S₈ → 8P₂S₅
---
- Left: C = 1, O = 1 + 2 = 3
- Right: C = 1, O = 2 → not balanced
- Try 2CO → 2C, 2O → need O₂ to supply 1 more O → but O₂ gives 2 O
- So: 2CO + O₂ → 2CO₂ → C = 2, O = 2 + 2 = 4 → right: 2×2 = 4 O ✔
- Answer:
2CO + O₂ → 2CO₂
---
- Left: C = 2, H = 6, O = 2
- Right: C = 1, H = 2, O = 2+1 = 3 → unbalanced
- Balance C: 2CO₂ → C = 2 ✔
- Balance H: 3H₂O → H = 6 ✔
- Now O: Right = 2×2 + 3×1 = 4 + 3 = 7 O
- Left: O₂ → need 7/2 → so 7/2 O₂ → multiply whole equation by 2:
- 2C₂H₆ + 7O₂ → 4CO₂ + 6H₂O
- Check:
- C: 4 = 4 ✔
- H: 12 = 12 ✔
- O: 14 = 8 + 6 = 14 ✔
- Answer:
2C₂H₆ + 7O₂ → 4CO₂ + 6H₂O
---
- C₂H₅OH = ethanol → C = 2, H = 6, O = 1
- Left: C = 2, H = 6, O = 1 + 2x (from O₂)
- Right: CO₂ → C = 1, O = 2; H₂O → H = 2, O = 1
- Balance C: 2CO₂ → C = 2 ✔
- Balance H: 3H₂O → H = 6 ✔
- O: Right = 2×2 + 3×1 = 4 + 3 = 7 O
- Left: from C₂H₅OH: 1 O, from O₂: 2x → total O = 1 + 2x = 7 → x = 3
- So O₂ = 3
- Answer:
C₂H₅OH + 3O₂ → 2CO₂ + 3H₂O
---
- Left: Fe = 1, S = 2, O = 2
- Right: Fe = 2, O = 3 + 2 = 5, S = 1
- Balance Fe: 2FeS₂ → Fe = 2 ✔
- S: 4 S → need 4SO₂ → S = 4 ✔
- O: Right: Fe₂O₃ has 3 O, 4SO₂ has 8 O → total 11 O
- Left: O₂ → need 11/2 → so 11/2 O₂ → multiply all by 2:
- 4FeS₂ + 11O₂ → 2Fe₂O₃ + 8SO₂
- Check:
- Fe: 4 = 4 ✔
- S: 8 = 8 ✔
- O: 22 = 6 + 16 = 22 ✔
- Answer:
4FeS₂ + 11O₂ → 2Fe₂O₃ + 8SO₂
---
- Left: P = 4, O = 3
- Right: P = 2, O = 5
- Balance P: 2P₂O₅ → P = 4 ✔
- O: 10 O → need O₃ → 10/3 → not integer
- Multiply by 3: 3P₄ + ? O₃ → 6P₂O₅ → P = 12 ✔
- O: 6×5 = 30 O → need 30/3 = 10 O₃
- So: 3P₄ + 10O₃ → 6P₂O₅
- Check:
- P: 12 = 12 ✔
- O: 30 = 30 ✔
- Answer:
3P₄ + 10O₃ → 6P₂O₅
---
- Left: N = 1, H = 3, O = 2
- Right: N = 2, O = 3 + 1 = 4, H = 2
- Balance N: 2NH₃ → N = 2 ✔
- H: 6 H → need 3H₂O → H = 6 ✔
- O: Right: N₂O₃ has 3, 3H₂O has 3 → total 6 O
- Left: O₂ → need 3 O₂ → 6 O ✔
- Answer:
2NH₃ + 3O₂ → N₂O₃ + 3H₂O
---
- Left: Si = 5, H = 11, Br = 2
- Right: Si = 1, H = 1, Br = 1
- Balance Si: 5Si → Si = 5 ✔
- H: 11H → need 11HBr → H = 11 ✔
- Br: 11Br → need 11/2 Br₂ → so 11/2 Br₂ → multiply by 2:
- 2Si₅H₁₁ + 11Br₂ → 10Si + 22HBr
- Check:
- Si: 10 = 10 ✔
- H: 22 = 22 ✔
- Br: 22 = 22 ✔
- Answer:
2Si₅H₁₁ + 11Br₂ → 10Si + 22HBr
---
- Left: Fe = 1, Cl = 3, Na = 1, O = 1, H = 1
- Right: Fe = 1, O = 3, H = 3, Na = 1, Cl = 1
- Balance Cl: 3NaCl → Cl = 3 → need 3NaOH
- Then Na = 3 → need 3NaOH
- O and H: 3NaOH → 3H, 3O → matches Fe(OH)₃
- Answer:
FeCl₃ + 3NaOH → Fe(OH)₃ + 3NaCl
---
- Left: Fe = 1, H = 2, O = 1
- Right: Fe = 2, O = 3, H = 2
- Balance Fe: 2Fe → Fe = 2 ✔
- O: 3 O → need 3H₂O → O = 3 ✔
- H: 6 H → need 3H₂ → H = 6 ✔
- Answer:
2Fe + 3H₂O → Fe₂O₃ + 3H₂
---
- Left: C = 10, H = 22, Cl = 2
- Right: C = 1, H = 1, Cl = 1
- Balance C: 10C → C = 10 ✔
- H: 22 H → need 22HCl → H = 22 ✔
- Cl: 22 Cl → need 11Cl₂ → Cl = 22 ✔
- Answer:
C₁₀H₂₂ + 11Cl₂ → 10C + 22HCl
---
- Left: Fe = 1, Cl = 3, Na = 2, S = 1, O = 4
- Right: Fe = 2, S = 3, O = 12, Na = 1, Cl = 1
- Balance Fe: 2FeCl₃ → Fe = 2 ✔
- S: 3SO₄ → need 3Na₂SO₄ → S = 3 ✔
- Na: 3×2 = 6 Na → need 6NaCl → Na = 6 ✔
- Cl: 2×3 = 6 → 6NaCl → Cl = 6 ✔
- Answer:
2FeCl₃ + 3Na₂SO₄ → Fe₂(SO₄)₃ + 6NaCl
---
- Left: Al = 1, H = 1, N = 1, O = 3
- Right: Al = 1, N = 3, O = 9, H = 2
- Balance N: 3HNO₃ → N = 3 ✔
- H: 3H → need 3/2 H₂ → so 3/2 H₂
- Multiply all by 2:
- 2Al + 6HNO₃ → 2Al(NO₃)₃ + 3H₂
- Check:
- Al: 2 = 2 ✔
- H: 6 = 6 ✔
- N: 6 = 6 ✔
- O: 18 = 18 ✔
- Answer:
2Al + 6HNO₃ → 2Al(NO₃)₃ + 3H₂
---
- Left: K = 1, H = 2, O = 1
- Right: K = 1, O = 1, H = 1 + 2 = 3 → not balanced
- H: Right has 3H → need 2KOH and 1H₂?
- Try: 2K + 2H₂O → 2KOH + H₂
- Check:
- K: 2 = 2 ✔
- H: 4 = 2 + 2 = 4 ✔
- O: 2 = 2 ✔
- Answer:
2K + 2H₂O → 2KOH + H₂
---
- Left: C = 3, H = 8, S = 8
- Right: C = 1, S = 2 + 1 = 3, H = 2
- Balance C: 3CS₂ → C = 3 ✔
- S: 3×2 = 6 S from CS₂ → need 2 more S → H₂S → 2H₂S → S = 2 → total S = 8 ✔
- H: 2H₂S → H = 4 → but need 8 H → so 4H₂S → H = 8 ✔
- But then S: 3CS₂ → 6S, 4H₂S → 4S → total 10S → too many
- Let’s set up:
- C₃H₈ → 3CS₂ → needs 3C, 6S
- H: 8H → need 4H₂S → 4S
- Total S: 6 + 4 = 10 → so need 10/8 = 5/4 S₈ → multiply by 4:
- 4C₃H₈ + 5S₈ → 12CS₂ + 16H₂S
- Check:
- C: 12 = 12 ✔
- H: 32 = 32 ✔
- S: 40 = 12×2 + 16×1 = 24 + 16 = 40 ✔
- Answer:
4C₃H₈ + 5S₈ → 12CS₂ + 16H₂S
---
- Left: Mg = 1, Cl = 2, Al = 1, O = 3, H = 3
- Right: Al = 1, Cl = 3, Mg = 1, O = 2, H = 2
- Balance Cl: 3MgCl₂ → Cl = 6 → need 2AlCl₃ → Cl = 6 ✔
- Al: 2Al(OH)₃ → Al = 2 ✔
- Mg: 3Mg(OH)₂ → Mg = 3 ✔
- O and H: 2Al(OH)₃ → 6O, 6H → 3Mg(OH)₂ → 6O, 6H → matches
- Answer:
3MgCl₂ + 2Al(OH)₃ → 2AlCl₃ + 3Mg(OH)₂
---
- Left: Zn = 1, Fe = 1, S = 2, O = 2
- Right: Zn = 1, Fe = 1, O = 1 + 2 = 3, S = 1
- Balance S: 2SO₂ → S = 2 ✔
- O: 2SO₂ → 4 O, FeO → 1 O → total 5 O
- Left: O₂ → need 5/2 → so 5/2 O₂ → multiply by 2:
- 2ZnFeS₂ + 5O₂ → 2Zn + 2FeO + 4SO₂
- Check:
- Zn: 2 = 2 ✔
- Fe: 2 = 2 ✔
- S: 4 = 4 ✔
- O: 10 = 2 + 8 = 10 ✔
- Answer:
2ZnFeS₂ + 5O₂ → 2Zn + 2FeO + 4SO₂
---
- Left: P = 4, O = 10 + 1 = 11, H = 2
- Right: P = 1, O = 4, H = 3
- Balance P: 4H₃PO₄ → P = 4 ✔
- H: 12 H → need 6H₂O → H = 12 ✔
- O: Left: P₄O₁₀ has 10, 6H₂O has 6 → total 16 O
Right: 4×4 = 16 O ✔
- Answer:
P₄O₁₀ + 6H₂O → 4H₃PO₄
---
- This is a disproportionation reaction.
- Left: K = 1, Cl = 1, O = 3
- Right: K = 1 + 1 = 2, Cl = 1 + 1 = 2, O = 0 + 4 = 4
- Balance K: 2KClO₃ → K = 2 ✔
- Cl: 2 → need 1KCl and 1KClO₄ → Cl = 2 ✔
- O: Left: 6 O → Right: 4 O → mismatch
- Try: 4KClO₃ → 3KCl + KClO₄
- K: 4 = 3 + 1 = 4 ✔
- Cl: 4 = 3 + 1 = 4 ✔
- O: 12 → right: 0 + 4 = 4 → no
- Try: 4KClO₃ → KCl + 3KClO₄ → K = 4, Cl = 4, O = 12 → right: 0 + 12 = 12 ✔
- But KClO₄ has 4 O → 3×4 = 12 → yes
- So: 4KClO₃ → KCl + 3KClO₄
- Check:
- K: 4 = 1 + 3 = 4 ✔
- Cl: 4 = 1 + 3 = 4 ✔
- O: 12 = 0 + 12 = 12 ✔
- Answer:
4KClO₃ → KCl + 3KClO₄
---
- Left: Mg = 3, N = 2, H = 2, O = 1
- Right: Mg = 1, O = 2, H = 2 + 3 = 5, N = 1
- Balance Mg: 3Mg(OH)₂ → Mg = 3 ✔
- N: 2NH₃ → N = 2 ✔
- H: 3Mg(OH)₂ → 6H, 2NH₃ → 6H → total 12 H → need 6H₂O → H = 12 ✔
- O: 6H₂O → 6 O → 3Mg(OH)₂ → 6 O ✔
- Answer:
Mg₃N₂ + 6H₂O → 3Mg(OH)₂ + 2NH₃
---
## ✔ Final Balanced Equations:
1. 2Ca + O₂ → 2CaO
2. H₂ + Cl₂ → 2HCl
3. 4P₄ + 5S₈ → 8P₂S₅
4. 2CO + O₂ → 2CO₂
5. 2C₂H₆ + 7O₂ → 4CO₂ + 6H₂O
6. C₂H₅OH + 3O₂ → 2CO₂ + 3H₂O
7. 4FeS₂ + 11O₂ → 2Fe₂O₃ + 8SO₂
8. 3P₄ + 10O₃ → 6P₂O₅
9. 2NH₃ + 3O₂ → N₂O₃ + 3H₂O
10. 2Si₅H₁₁ + 11Br₂ → 10Si + 22HBr
11. FeCl₃ + 3NaOH → Fe(OH)₃ + 3NaCl
12. 2Fe + 3H₂O → Fe₂O₃ + 3H₂
13. C₁₀H₂₂ + 11Cl₂ → 10C + 22HCl
14. 2FeCl₃ + 3Na₂SO₄ → Fe₂(SO₄)₃ + 6NaCl
15. 2Al + 6HNO₃ → 2Al(NO₃)₃ + 3H₂
16. 2K + 2H₂O → 2KOH + H₂
17. 4C₃H₈ + 5S₈ → 12CS₂ + 16H₂S
18. 3MgCl₂ + 2Al(OH)₃ → 2AlCl₃ + 3Mg(OH)₂
19. 2ZnFeS₂ + 5O₂ → 2Zn + 2FeO + 4SO₂
20. P₄O₁₀ + 6H₂O → 4H₃PO₄
21. 4KClO₃ → KCl + 3KClO₄
22. Mg₃N₂ + 6H₂O → 3Mg(OH)₂ + 2NH₃
---
✔ All equations are now balanced. You can use this as your completed worksheet!
---
1. Ca + O₂ → CaO
- Left: Ca = 1, O = 2
- Right: Ca = 1, O = 1 → Not balanced
- Balance O: Need 2 CaO on right → 2 CaO → now need 2 Ca on left
- Answer:
2Ca + O₂ → 2CaO
---
2. H₂ + Cl₂ → HCl
- Left: H = 2, Cl = 2
- Right: H = 1, Cl = 1 → Need 2 HCl
- Answer:
H₂ + Cl₂ → 2HCl
---
3. P₄ + S₈ → P₂S₅
- Left: P = 4, S = 8
- Right: P = 2, S = 5 → LCM for P and S needed
- Target: Make P = 4, S = 10? But S₈ has 8 S → try to match.
- Use 2P₂S₅ → P = 4, S = 10 → but S₈ has 8 S → not divisible
- Try 4P₂S₅ → P = 8, S = 20 → need P₄ × 2 = 8 P, S₈ × 2.5 → not integer
- Try P₄ + 5/4 S₈ → 2P₂S₅ → multiply all by 4:
- 4P₄ + 5S₈ → 8P₂S₅ → check:
- P: 16 = 16 ✔
- S: 40 = 40 ✔
- Answer:
4P₄ + 5S₈ → 8P₂S₅
---
4. CO + O₂ → CO₂
- Left: C = 1, O = 1 + 2 = 3
- Right: C = 1, O = 2 → not balanced
- Try 2CO → 2C, 2O → need O₂ to supply 1 more O → but O₂ gives 2 O
- So: 2CO + O₂ → 2CO₂ → C = 2, O = 2 + 2 = 4 → right: 2×2 = 4 O ✔
- Answer:
2CO + O₂ → 2CO₂
---
5. C₂H₆ + O₂ → CO₂ + H₂O
- Left: C = 2, H = 6, O = 2
- Right: C = 1, H = 2, O = 2+1 = 3 → unbalanced
- Balance C: 2CO₂ → C = 2 ✔
- Balance H: 3H₂O → H = 6 ✔
- Now O: Right = 2×2 + 3×1 = 4 + 3 = 7 O
- Left: O₂ → need 7/2 → so 7/2 O₂ → multiply whole equation by 2:
- 2C₂H₆ + 7O₂ → 4CO₂ + 6H₂O
- Check:
- C: 4 = 4 ✔
- H: 12 = 12 ✔
- O: 14 = 8 + 6 = 14 ✔
- Answer:
2C₂H₆ + 7O₂ → 4CO₂ + 6H₂O
---
6. C₂H₅OH + O₂ → CO₂ + H₂O
- C₂H₅OH = ethanol → C = 2, H = 6, O = 1
- Left: C = 2, H = 6, O = 1 + 2x (from O₂)
- Right: CO₂ → C = 1, O = 2; H₂O → H = 2, O = 1
- Balance C: 2CO₂ → C = 2 ✔
- Balance H: 3H₂O → H = 6 ✔
- O: Right = 2×2 + 3×1 = 4 + 3 = 7 O
- Left: from C₂H₅OH: 1 O, from O₂: 2x → total O = 1 + 2x = 7 → x = 3
- So O₂ = 3
- Answer:
C₂H₅OH + 3O₂ → 2CO₂ + 3H₂O
---
7. FeS₂ + O₂ → Fe₂O₃ + SO₂
- Left: Fe = 1, S = 2, O = 2
- Right: Fe = 2, O = 3 + 2 = 5, S = 1
- Balance Fe: 2FeS₂ → Fe = 2 ✔
- S: 4 S → need 4SO₂ → S = 4 ✔
- O: Right: Fe₂O₃ has 3 O, 4SO₂ has 8 O → total 11 O
- Left: O₂ → need 11/2 → so 11/2 O₂ → multiply all by 2:
- 4FeS₂ + 11O₂ → 2Fe₂O₃ + 8SO₂
- Check:
- Fe: 4 = 4 ✔
- S: 8 = 8 ✔
- O: 22 = 6 + 16 = 22 ✔
- Answer:
4FeS₂ + 11O₂ → 2Fe₂O₃ + 8SO₂
---
8. P₄ + O₃ → P₂O₅
- Left: P = 4, O = 3
- Right: P = 2, O = 5
- Balance P: 2P₂O₅ → P = 4 ✔
- O: 10 O → need O₃ → 10/3 → not integer
- Multiply by 3: 3P₄ + ? O₃ → 6P₂O₅ → P = 12 ✔
- O: 6×5 = 30 O → need 30/3 = 10 O₃
- So: 3P₄ + 10O₃ → 6P₂O₅
- Check:
- P: 12 = 12 ✔
- O: 30 = 30 ✔
- Answer:
3P₄ + 10O₃ → 6P₂O₅
---
9. NH₃ + O₂ → N₂O₃ + H₂O
- Left: N = 1, H = 3, O = 2
- Right: N = 2, O = 3 + 1 = 4, H = 2
- Balance N: 2NH₃ → N = 2 ✔
- H: 6 H → need 3H₂O → H = 6 ✔
- O: Right: N₂O₃ has 3, 3H₂O has 3 → total 6 O
- Left: O₂ → need 3 O₂ → 6 O ✔
- Answer:
2NH₃ + 3O₂ → N₂O₃ + 3H₂O
---
10. Si₅H₁₁ + Br₂ → Si + HBr
- Left: Si = 5, H = 11, Br = 2
- Right: Si = 1, H = 1, Br = 1
- Balance Si: 5Si → Si = 5 ✔
- H: 11H → need 11HBr → H = 11 ✔
- Br: 11Br → need 11/2 Br₂ → so 11/2 Br₂ → multiply by 2:
- 2Si₅H₁₁ + 11Br₂ → 10Si + 22HBr
- Check:
- Si: 10 = 10 ✔
- H: 22 = 22 ✔
- Br: 22 = 22 ✔
- Answer:
2Si₅H₁₁ + 11Br₂ → 10Si + 22HBr
---
11. FeCl₃ + NaOH → Fe(OH)₃ + NaCl
- Left: Fe = 1, Cl = 3, Na = 1, O = 1, H = 1
- Right: Fe = 1, O = 3, H = 3, Na = 1, Cl = 1
- Balance Cl: 3NaCl → Cl = 3 → need 3NaOH
- Then Na = 3 → need 3NaOH
- O and H: 3NaOH → 3H, 3O → matches Fe(OH)₃
- Answer:
FeCl₃ + 3NaOH → Fe(OH)₃ + 3NaCl
---
12. Fe + H₂O → Fe₂O₃ + H₂
- Left: Fe = 1, H = 2, O = 1
- Right: Fe = 2, O = 3, H = 2
- Balance Fe: 2Fe → Fe = 2 ✔
- O: 3 O → need 3H₂O → O = 3 ✔
- H: 6 H → need 3H₂ → H = 6 ✔
- Answer:
2Fe + 3H₂O → Fe₂O₃ + 3H₂
---
13. C₁₀H₂₂ + Cl₂ → C + HCl
- Left: C = 10, H = 22, Cl = 2
- Right: C = 1, H = 1, Cl = 1
- Balance C: 10C → C = 10 ✔
- H: 22 H → need 22HCl → H = 22 ✔
- Cl: 22 Cl → need 11Cl₂ → Cl = 22 ✔
- Answer:
C₁₀H₂₂ + 11Cl₂ → 10C + 22HCl
---
14. FeCl₃ + Na₂SO₄ → Fe₂(SO₄)₃ + NaCl
- Left: Fe = 1, Cl = 3, Na = 2, S = 1, O = 4
- Right: Fe = 2, S = 3, O = 12, Na = 1, Cl = 1
- Balance Fe: 2FeCl₃ → Fe = 2 ✔
- S: 3SO₄ → need 3Na₂SO₄ → S = 3 ✔
- Na: 3×2 = 6 Na → need 6NaCl → Na = 6 ✔
- Cl: 2×3 = 6 → 6NaCl → Cl = 6 ✔
- Answer:
2FeCl₃ + 3Na₂SO₄ → Fe₂(SO₄)₃ + 6NaCl
---
15. Al + HNO₃ → Al(NO₃)₃ + H₂
- Left: Al = 1, H = 1, N = 1, O = 3
- Right: Al = 1, N = 3, O = 9, H = 2
- Balance N: 3HNO₃ → N = 3 ✔
- H: 3H → need 3/2 H₂ → so 3/2 H₂
- Multiply all by 2:
- 2Al + 6HNO₃ → 2Al(NO₃)₃ + 3H₂
- Check:
- Al: 2 = 2 ✔
- H: 6 = 6 ✔
- N: 6 = 6 ✔
- O: 18 = 18 ✔
- Answer:
2Al + 6HNO₃ → 2Al(NO₃)₃ + 3H₂
---
16. K + H₂O → KOH + H₂
- Left: K = 1, H = 2, O = 1
- Right: K = 1, O = 1, H = 1 + 2 = 3 → not balanced
- H: Right has 3H → need 2KOH and 1H₂?
- Try: 2K + 2H₂O → 2KOH + H₂
- Check:
- K: 2 = 2 ✔
- H: 4 = 2 + 2 = 4 ✔
- O: 2 = 2 ✔
- Answer:
2K + 2H₂O → 2KOH + H₂
---
17. C₃H₈ + S₈ → CS₂ + H₂S
- Left: C = 3, H = 8, S = 8
- Right: C = 1, S = 2 + 1 = 3, H = 2
- Balance C: 3CS₂ → C = 3 ✔
- S: 3×2 = 6 S from CS₂ → need 2 more S → H₂S → 2H₂S → S = 2 → total S = 8 ✔
- H: 2H₂S → H = 4 → but need 8 H → so 4H₂S → H = 8 ✔
- But then S: 3CS₂ → 6S, 4H₂S → 4S → total 10S → too many
- Let’s set up:
- C₃H₈ → 3CS₂ → needs 3C, 6S
- H: 8H → need 4H₂S → 4S
- Total S: 6 + 4 = 10 → so need 10/8 = 5/4 S₈ → multiply by 4:
- 4C₃H₈ + 5S₈ → 12CS₂ + 16H₂S
- Check:
- C: 12 = 12 ✔
- H: 32 = 32 ✔
- S: 40 = 12×2 + 16×1 = 24 + 16 = 40 ✔
- Answer:
4C₃H₈ + 5S₈ → 12CS₂ + 16H₂S
---
18. MgCl₂ + Al(OH)₃ → AlCl₃ + Mg(OH)₂
- Left: Mg = 1, Cl = 2, Al = 1, O = 3, H = 3
- Right: Al = 1, Cl = 3, Mg = 1, O = 2, H = 2
- Balance Cl: 3MgCl₂ → Cl = 6 → need 2AlCl₃ → Cl = 6 ✔
- Al: 2Al(OH)₃ → Al = 2 ✔
- Mg: 3Mg(OH)₂ → Mg = 3 ✔
- O and H: 2Al(OH)₃ → 6O, 6H → 3Mg(OH)₂ → 6O, 6H → matches
- Answer:
3MgCl₂ + 2Al(OH)₃ → 2AlCl₃ + 3Mg(OH)₂
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19. ZnFeS₂ + O₂ → Zn + FeO + SO₂
- Left: Zn = 1, Fe = 1, S = 2, O = 2
- Right: Zn = 1, Fe = 1, O = 1 + 2 = 3, S = 1
- Balance S: 2SO₂ → S = 2 ✔
- O: 2SO₂ → 4 O, FeO → 1 O → total 5 O
- Left: O₂ → need 5/2 → so 5/2 O₂ → multiply by 2:
- 2ZnFeS₂ + 5O₂ → 2Zn + 2FeO + 4SO₂
- Check:
- Zn: 2 = 2 ✔
- Fe: 2 = 2 ✔
- S: 4 = 4 ✔
- O: 10 = 2 + 8 = 10 ✔
- Answer:
2ZnFeS₂ + 5O₂ → 2Zn + 2FeO + 4SO₂
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20. P₄O₁₀ + H₂O → H₃PO₄
- Left: P = 4, O = 10 + 1 = 11, H = 2
- Right: P = 1, O = 4, H = 3
- Balance P: 4H₃PO₄ → P = 4 ✔
- H: 12 H → need 6H₂O → H = 12 ✔
- O: Left: P₄O₁₀ has 10, 6H₂O has 6 → total 16 O
Right: 4×4 = 16 O ✔
- Answer:
P₄O₁₀ + 6H₂O → 4H₃PO₄
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21. KClO₃ → KCl + KClO₄
- This is a disproportionation reaction.
- Left: K = 1, Cl = 1, O = 3
- Right: K = 1 + 1 = 2, Cl = 1 + 1 = 2, O = 0 + 4 = 4
- Balance K: 2KClO₃ → K = 2 ✔
- Cl: 2 → need 1KCl and 1KClO₄ → Cl = 2 ✔
- O: Left: 6 O → Right: 4 O → mismatch
- Try: 4KClO₃ → 3KCl + KClO₄
- K: 4 = 3 + 1 = 4 ✔
- Cl: 4 = 3 + 1 = 4 ✔
- O: 12 → right: 0 + 4 = 4 → no
- Try: 4KClO₃ → KCl + 3KClO₄ → K = 4, Cl = 4, O = 12 → right: 0 + 12 = 12 ✔
- But KClO₄ has 4 O → 3×4 = 12 → yes
- So: 4KClO₃ → KCl + 3KClO₄
- Check:
- K: 4 = 1 + 3 = 4 ✔
- Cl: 4 = 1 + 3 = 4 ✔
- O: 12 = 0 + 12 = 12 ✔
- Answer:
4KClO₃ → KCl + 3KClO₄
---
22. Mg₃N₂ + H₂O → Mg(OH)₂ + NH₃
- Left: Mg = 3, N = 2, H = 2, O = 1
- Right: Mg = 1, O = 2, H = 2 + 3 = 5, N = 1
- Balance Mg: 3Mg(OH)₂ → Mg = 3 ✔
- N: 2NH₃ → N = 2 ✔
- H: 3Mg(OH)₂ → 6H, 2NH₃ → 6H → total 12 H → need 6H₂O → H = 12 ✔
- O: 6H₂O → 6 O → 3Mg(OH)₂ → 6 O ✔
- Answer:
Mg₃N₂ + 6H₂O → 3Mg(OH)₂ + 2NH₃
---
## ✔ Final Balanced Equations:
1. 2Ca + O₂ → 2CaO
2. H₂ + Cl₂ → 2HCl
3. 4P₄ + 5S₈ → 8P₂S₅
4. 2CO + O₂ → 2CO₂
5. 2C₂H₆ + 7O₂ → 4CO₂ + 6H₂O
6. C₂H₅OH + 3O₂ → 2CO₂ + 3H₂O
7. 4FeS₂ + 11O₂ → 2Fe₂O₃ + 8SO₂
8. 3P₄ + 10O₃ → 6P₂O₅
9. 2NH₃ + 3O₂ → N₂O₃ + 3H₂O
10. 2Si₅H₁₁ + 11Br₂ → 10Si + 22HBr
11. FeCl₃ + 3NaOH → Fe(OH)₃ + 3NaCl
12. 2Fe + 3H₂O → Fe₂O₃ + 3H₂
13. C₁₀H₂₂ + 11Cl₂ → 10C + 22HCl
14. 2FeCl₃ + 3Na₂SO₄ → Fe₂(SO₄)₃ + 6NaCl
15. 2Al + 6HNO₃ → 2Al(NO₃)₃ + 3H₂
16. 2K + 2H₂O → 2KOH + H₂
17. 4C₃H₈ + 5S₈ → 12CS₂ + 16H₂S
18. 3MgCl₂ + 2Al(OH)₃ → 2AlCl₃ + 3Mg(OH)₂
19. 2ZnFeS₂ + 5O₂ → 2Zn + 2FeO + 4SO₂
20. P₄O₁₀ + 6H₂O → 4H₃PO₄
21. 4KClO₃ → KCl + 3KClO₄
22. Mg₃N₂ + 6H₂O → 3Mg(OH)₂ + 2NH₃
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✔ All equations are now balanced. You can use this as your completed worksheet!
Parent Tip: Review the logic above to help your child master the concept of balancing equations worksheet 2 answers.
![49 Balancing Chemical Equations Worksheets [with Answers]](/images2/balancing-equations-worksheet-2-answers/balancing-equations-worksheet-2-answers-4.jpg)
