49 Balancing Chemical Equations Worksheets [with Answers] - Free Printable

Here is the fully balanced version of all 17 chemical equations from your Grade 10 Science homework sheet, along with a clear explanation for each.

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🔢 Balancing Chemical Equations – Key Principle:

> The number of atoms of each element must be equal on both sides (reactants and products) — Law of Conservation of Mass.

We balance by placing coefficients (numbers in front of molecules) — never change subscripts!

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## ✔ Balanced Equations with Explanations:

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1. N₂ + H₂ → NH₃

Balanced:
N₂ + 3H₂ → 2NH₃

🔹 *Explanation:*
- Left: 2 N, 2 H
- Right: 1 N, 3 H
→ Add coefficient 2 to NH₃ → now 2 N, 6 H on right
→ Add coefficient 3 to H₂ → now 6 H on left
✔ Balanced: 2 N, 6 H on both sides

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2. S₈ + O₂ → SO₃

Balanced:
S₈ + 12O₂ → 8SO₃

🔹 *Explanation:*
- S₈ has 8 sulfur atoms → need 8 SO₃ on right → 8 S, 24 O
- O₂ provides 2 O per molecule → need 12 O₂ to get 24 O
✔ 8 S, 24 O on both sides

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3. HgO → Hg + O₂

Balanced:
2HgO → 2Hg + O₂

🔹 *Explanation:*
- Left: 1 Hg, 1 O
- Right: 1 Hg, 2 O → imbalance
→ Put 2 in front of HgO → 2 Hg, 2 O
→ Put 2 in front of Hg → 2 Hg
→ O₂ already has 2 O
✔ 2 Hg, 2 O on both sides

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4. Zn + HCl → ZnCl₂ + H₂

Balanced:
Zn + 2HCl → ZnCl₂ + H₂

🔹 *Explanation:*
- Right: ZnCl₂ has 2 Cl → need 2 HCl on left
- 2 HCl gives 2 H → forms H₂ (which has 2 H)
✔ Zn:1, H:2, Cl:2 on both sides

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5. SiCl₄ + H₂O → H₄SiO₄ + HCl

Balanced:
SiCl₄ + 4H₂O → H₄SiO₄ + 4HCl

🔹 *Explanation:*
- Right: H₄SiO₄ has 4 H, 1 Si, 4 O; HCl has 1 H, 1 Cl
→ Total right: Si=1, O=4, H=4+? (depends on HCl)
→ Left: SiCl₄ has 1 Si, 4 Cl → need 4 HCl on right → adds 4 H
→ So total H on right = 4 (from H₄SiO₄) + 4 (from 4 HCl) = 8 H
→ Need 4 H₂O on left → 8 H, 4 O
✔ Si:1, Cl:4, H:8, O:4 on both sides

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6. Na + H₂O → NaOH + H₂

Balanced:
2Na + 2H₂O → 2NaOH + H₂

🔹 *Explanation:*
- Try 2 Na → 2 NaOH → 2 Na, 2 O, 2 H from NaOH + 2 H from H₂ = 4 H total
- Left: 2 H₂O → 4 H, 2 O
✔ Na:2, H:4, O:2 on both sides

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7. H₃PO₄ → H₄P₂O₇ + H₂O

Balanced:
2H₃PO₄ → H₄P₂O₇ + H₂O

🔹 *Explanation:*
- Right: H₄P₂O₇ has 4 H, 2 P, 7 O; H₂O has 2 H, 1 O → total: 6 H, 2 P, 8 O
- Left: 2 H₃PO₄ → 6 H, 2 P, 8 O
✔ Perfect match!

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8. Si₂H₃ + O₂ → SiO₂ + H₂O

⚠️ Note: Si₂H₃ is not a stable compound — likely meant to be SiH₄ (silane). But if we proceed as written:

Actually, Si₂H₆ (disilane) is common, but let’s assume typo or proceed with given formula.

But Si₂H₃ doesn’t make sense stoichiometrically. Let’s check if it’s SiH₄?

If it were SiH₄, balanced equation would be:
SiH₄ + 2O₂ → SiO₂ + 2H₂O

But since it's written as Si₂H₃, let’s try to balance it as-is:

Try:
4Si₂H₃ + 11O₂ → 8SiO₂ + 6H₂O

Check atoms:
- Left: Si=8, H=12, O=22
- Right: Si=8, O=16+6=22, H=12
✔ Works!

So:

Balanced:
4Si₂H₃ + 11O₂ → 8SiO₂ + 6H₂O

*(This is unusual — double-check if original was meant to be SiH₄)*

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9. Al(OH)₃ + H₂SO₄ → Al₂(SO₄)₃ + H₂O

Balanced:
2Al(OH)₃ + 3H₂SO₄ → Al₂(SO₄)₃ + 6H₂O

🔹 *Explanation:*
- Right: Al₂(SO₄)₃ → 2 Al, 3 S, 12 O
- Left: Need 2 Al(OH)₃ → 2 Al, 6 O, 6 H
- Need 3 H₂SO₄ → 6 H, 3 S, 12 O
→ Total left: Al=2, S=3, O=6+12=18, H=6+6=12
→ Right: Al₂(SO₄)₃ has 2 Al, 3 S, 12 O; 6 H₂O has 12 H, 6 O → total O=18, H=12
✔ Balanced!

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10. Fe + O₂ → Fe₂O₃

Balanced:
4Fe + 3O₂ → 2Fe₂O₃

🔹 *Explanation:*
- Right: 2Fe₂O₃ → 4 Fe, 6 O
- Left: 4 Fe, 3 O₂ → 6 O
✔ Balanced

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11. Fe₂(SO₄)₃ + KOH → K₂SO₄ + Fe(OH)₃

Balanced:
Fe₂(SO₄)₃ + 6KOH → 3K₂SO₄ + 2Fe(OH)₃

🔹 *Explanation:*
- Left: Fe₂(SO₄)₃ → 2 Fe, 3 S, 12 O
- Right: 2Fe(OH)₃ → 2 Fe, 6 O, 6 H
- 3K₂SO₄ → 6 K, 3 S, 12 O
→ Total right: Fe=2, S=3, O=6+12=18, H=6, K=6
→ Left: 6KOH → 6 K, 6 O, 6 H → plus Fe₂(SO₄)₃ → 2 Fe, 3 S, 12 O → total O=18
✔ All elements balanced

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12. FeS₂ + O₂ → Fe₂O₃ + SO₂

Balanced:
4FeS₂ + 11O₂ → 2Fe₂O₃ + 8SO₂

🔹 *Explanation:*
- Right: 2Fe₂O₃ → 4 Fe, 6 O; 8SO₂ → 8 S, 16 O → total: 4 Fe, 8 S, 22 O
- Left: 4FeS₂ → 4 Fe, 8 S; 11O₂ → 22 O
✔ Balanced

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13. Al + FeO → Al₂O₃ + Fe

Balanced:
2Al + 3FeO → Al₂O₃ + 3Fe

🔹 *Explanation:*
- Right: Al₂O₃ → 2 Al, 3 O; 3Fe → 3 Fe
- Left: 2 Al; 3FeO → 3 Fe, 3 O
✔ Balanced

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14. Na₂CO₃ + HCl → NaCl + H₂O + CO₂

Balanced:
Na₂CO₃ + 2HCl → 2NaCl + H₂O + CO₂

🔹 *Explanation:*
- Left: Na₂CO₃ → 2 Na, 1 C, 3 O; 2HCl → 2 H, 2 Cl
- Right: 2NaCl → 2 Na, 2 Cl; H₂O → 2 H, 1 O; CO₂ → 1 C, 2 O → total: 2 Na, 2 Cl, 2 H, 1 C, 3 O
✔ Balanced

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15. K + Br₂ → KBr

Balanced:
2K + Br₂ → 2KBr

🔹 *Explanation:*
- Right: 2KBr → 2 K, 2 Br
- Left: 2 K, Br₂ → 2 Br
✔ Balanced

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16. P₄ + O₂ → P₂O₅

Balanced:
P₄ + 5O₂ → 2P₂O₅

🔹 *Explanation:*
- Right: 2P₂O₅ → 4 P, 10 O
- Left: P₄ → 4 P; 5O₂ → 10 O
✔ Balanced

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17. C₂H₂ + O₂ → CO₂ + H₂O

Balanced:
2C₂H₂ + 5O₂ → 4CO₂ + 2H₂O

🔹 *Explanation:*
- Right: 4CO₂ → 4 C, 8 O; 2H₂O → 4 H, 2 O → total: 4 C, 4 H, 10 O
- Left: 2C₂H₂ → 4 C, 4 H; 5O₂ → 10 O
✔ Balanced

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## 📝 Final Answer Summary:

Here are all 17 equations balanced:

1. N₂ + 3H₂ → 2NH₃
2. S₈ + 12O₂ → 8SO₃
3. 2HgO → 2Hg + O₂
4. Zn + 2HCl → ZnCl₂ + H₂
5. SiCl₄ + 4H₂O → H₄SiO₄ + 4HCl
6. 2Na + 2H₂O → 2NaOH + H₂
7. 2H₃PO₄ → H₄P₂O₇ + H₂O
8. 4Si₂H₃ + 11O₂ → 8SiO₂ + 6H₂O *(unusual compound — verify if intended)*
9. 2Al(OH)₃ + 3H₂SO₄ → Al₂(SO₄)₃ + 6H₂O
10. 4Fe + 3O₂ → 2Fe₂O₃
11. Fe₂(SO₄)₃ + 6KOH → 3K₂SO₄ + 2Fe(OH)₃
12. 4FeS₂ + 11O₂ → 2Fe₂O₃ + 8SO₂
13. 2Al + 3FeO → Al₂O₃ + 3Fe
14. Na₂CO₃ + 2HCl → 2NaCl + H₂O + CO₂
15. 2K + Br₂ → 2KBr
16. P₄ + 5O₂ → 2P₂O₅
17. 2C₂H₂ + 5O₂ → 4CO₂ + 2H₂O

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✔ You can now confidently fill in your worksheet!

Let me know if you want step-by-step balancing for any specific one!