Balancing Equations Worksheets - Free Printable

Let's solve each of these balancing equations and identify the type of reaction for each. I'll go step-by-step through all 20 problems.

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1. K(s) + Br₂(l) → KBr(s)

Balanced Equation:
K(s) + Br₂(l) → 2KBr(s)

Explanation:
Potassium (K) is a metal, bromine (Br₂) is a diatomic element. They form potassium bromide (KBr). To balance:
- 2 K atoms on right → need 2 K on left
- 2 Br atoms on left → need 2 Br on right → so 2KBr

✔ Balanced: 2K(s) + Br₂(l) → 2KBr(s)

Type of Reaction: Synthesis (Combination) – two elements combine to form one compound.

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2. Al(s) + O₂(g) → Al₂O₃(s)

Balanced Equation:
4Al(s) + 3O₂(g) → 2Al₂O₃(s)

Explanation:
Aluminum and oxygen form aluminum oxide.
- Al₂O₃ has 2 Al and 3 O
- O₂ is diatomic → need even number of O atoms
- LCM of 3 and 2 is 6 → use 2Al₂O₃ (6 O, 4 Al)
- So 4 Al and 3 O₂

✔ Balanced: 4Al(s) + 3O₂(g) → 2Al₂O₃(s)

Type: Synthesis

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3. Cl₂(g) + KI(aq) → KCl(aq) + I₂(s)

Balanced Equation:
Cl₂(g) + 2KI(aq) → 2KCl(aq) + I₂(s)

Explanation:
Chlorine displaces iodine from KI.
- Iodine is diatomic (I₂), so need 2 I on both sides
- Thus, 2KI and 2KCl

✔ Balanced: Cl₂(g) + 2KI(aq) → 2KCl(aq) + I₂(s)

Type: Single Replacement – Cl replaces I in KI

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4. KOH(aq) + H₃PO₄(aq) → K₃PO₄(aq) + H₂O(l)

Balanced Equation:
3KOH(aq) + H₃PO₄(aq) → K₃PO₄(aq) + 3H₂O(l)

Explanation:
Acid-base neutralization.
- H₃PO₄ has 3 H⁺, KOH provides OH⁻
- Need 3 KOH to neutralize H₃PO₄ → 3 H₂O

✔ Balanced: 3KOH(aq) + H₃PO₄(aq) → K₃PO₄(aq) + 3H₂O(l)

Type: Double Replacement (with acid-base neutralization)

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5. P(s) + O₂(g) → P₂O₅(g)

Balanced Equation:
4P(s) + 5O₂(g) → 2P₂O₅(g)

Explanation:
Phosphorus and oxygen form diphosphorus pentoxide.
- P₂O₅ has 2 P and 5 O
- O₂ is diatomic → need 5 O₂ for 10 O → 2P₂O₅ gives 10 O
- So 4P and 5O₂

✔ Balanced: 4P(s) + 5O₂(g) → 2P₂O₅(g)

Type: Synthesis

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6. KClO₃(s) → KCl(s) + O₂(g)

Balanced Equation:
2KClO₃(s) → 2KCl(s) + 3O₂(g)

Explanation:
Decomposition of potassium chlorate.
- KClO₃ → KCl + O₂
- O₂ is diatomic; 3 O₂ = 6 O atoms → need 2 KClO₃ (6 O)
- 2KClO₃ → 2KCl + 3O₂

✔ Balanced: 2KClO₃(s) → 2KCl(s) + 3O₂(g)

Type: Decomposition

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7. BaCl₂(aq) + Na₃PO₄(aq) → NaCl(aq) + Ba₃(PO₄)₂(s)

Balanced Equation:
3BaCl₂(aq) + 2Na₃PO₄(aq) → 6NaCl(aq) + Ba₃(PO₄)₂(s)

Explanation:
Precipitation reaction: Ba₃(PO₄)₂ is insoluble.
- Ba₃(PO₄)₂ requires 3 Ba²⁺ and 2 PO₄³⁻
- So need 3 BaCl₂ and 2 Na₃PO₄
- Products: 6 NaCl and 1 Ba₃(PO₄)₂

✔ Balanced: 3BaCl₂(aq) + 2Na₃PO₄(aq) → 6NaCl(aq) + Ba₃(PO₄)₂(s)

Type: Double Replacement (precipitation)

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8. C₃H₈(g) + O₂(g) → CO₂(g) + H₂O(g)

Balanced Equation:
C₃H₈(g) + 5O₂(g) → 3CO₂(g) + 4H₂O(g)

Explanation:
Combustion of propane.
- C₃H₈ → 3 CO₂ and 4 H₂O (since 8 H → 4 H₂O)
- O₂ needed: 3×2 = 6 O from CO₂, 4×1 = 4 O from H₂O → total 10 O → 5 O₂

✔ Balanced: C₃H₈(g) + 5O₂(g) → 3CO₂(g) + 4H₂O(g)

Type: Combustion

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9. FeS(aq) + H₂SO₄(aq) → Fe₂(SO₄)₃(aq) + H₂S(g)

Wait — this seems incorrect. Iron(II) sulfide reacts with sulfuric acid:

But FeS → Fe²⁺, not Fe³⁺. So correct product should be FeSO₄, not Fe₂(SO₄)₃.

But let’s assume it's as written. But that would imply Fe³⁺, which is inconsistent.

Actually, FeS + H₂SO₄ → FeSO₄ + H₂S is correct.

So likely typo. Let's fix:

Corrected: FeS(s) + H₂SO₄(aq) → FeSO₄(aq) + H₂S(g)

But original says Fe₂(SO₄)₃ → implies Fe³⁺

So if we assume Fe₂(SO₄)₃, then iron must be Fe³⁺ → so reactant should be Fe₂O₃ or FeCl₃, not FeS.

So probably error.

But let's try balancing as given:
FeS + H₂SO₄ → Fe₂(SO₄)₃ + H₂S

Left: Fe=1, S=2 (1 from FeS, 1 from H₂SO₄), H=2, O=4
Right: Fe=2, S=3+1=4? Wait — Fe₂(SO₄)₃ has 3 SO₄ → 3 S, plus H₂S has 1 S → total 4 S

So need more S.

Try:

2FeS + 3H₂SO₄ → Fe₂(SO₄)₃ + 3H₂S

Check:
Left: Fe=2, S=2+3=5, H=6, O=12
Right: Fe=2, S=3 (in sulfate) + 3 (in H₂S) = 6 → no

Wait: Fe₂(SO₄)₃ has 3 S, 3 H₂S has 3 S → total 6 S
Left: 2FeS → 2S, 3H₂SO₄ → 3S → total 5S → still off

Better:
2FeS + 4H₂SO₄ → Fe₂(SO₄)₃ + 4H₂S + S? No.

This suggests inconsistency.

Conclusion: The equation is likely wrong. FeS with acid produces Fe²⁺ and H₂S.

So correct balanced equation is:
FeS(s) + H₂SO₄(aq) → FeSO₄(aq) + H₂S(g)

✔ Already balanced.

But per problem: FeS(aq) + H₂SO₄(aq) → Fe₂(SO₄)₃(aq) + H₂S(g) — this is chemically incorrect.

Assuming it's a typo and should be FeS → FeSO₄, then:

FeS(s) + H₂SO₄(aq) → FeSO₄(aq) + H₂S(g) — balanced as is.

Type: Double Replacement

But if we proceed as written, it's unbalanced and chemically invalid.

So I’ll assume typo and use:

✔ FeS(s) + H₂SO₄(aq) → FeSO₄(aq) + H₂S(g) — balanced

Type: Double Replacement

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10. AlBr₃(s) → Al(s) + Br₂(l)

Balanced Equation:
2AlBr₃(s) → 2Al(s) + 3Br₂(l)

Explanation:
Decomposition of aluminum bromide.
- AlBr₃ → Al + Br₂
- Br₂ is diatomic → need 3Br₂ for 6 Br → so 2AlBr₃

✔ Balanced: 2AlBr₃(s) → 2Al(s) + 3Br₂(l)

Type: Decomposition

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11. C₄H₁₀(l) + O₂(g) → CO₂(g) + H₂O(g)

Balanced Equation:
2C₄H₁₀(l) + 13O₂(g) → 8CO₂(g) + 10H₂O(g)

Explanation:
Combustion of butane.
- C₄H₁₀ → 4 CO₂ and 5 H₂O
- For 1 molecule: 4C → 4CO₂, 10H → 5H₂O
- O needed: 4×2 + 5×1 = 8+5 = 13 O → 13/2 O₂ → multiply by 2

So: 2C₄H₁₀ + 13O₂ → 8CO₂ + 10H₂O

✔ Balanced

Type: Combustion

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12. Na(s) + CuCl₂(aq) → NaCl(aq) + Cu(s)

Balanced Equation:
2Na(s) + CuCl₂(aq) → 2NaCl(aq) + Cu(s)

Explanation:
Sodium displaces copper from its salt.
- CuCl₂ has 2 Cl → need 2 NaCl → 2 Na

✔ Balanced

Type: Single Replacement

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13. K(s) + HCl(aq) → KCl(aq) + H₂(g)

Balanced Equation:
2K(s) + 2HCl(aq) → 2KCl(aq) + H₂(g)

Explanation:
Potassium reacts with acid to produce hydrogen gas.
- H₂ is diatomic → need 2 H⁺ → 2 HCl → 2 KCl

✔ Balanced

Type: Single Replacement

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14. Fe(OH)₃(s) → Fe₂O₃(s) + H₂O(l)

Balanced Equation:
2Fe(OH)₃(s) → Fe₂O₃(s) + 3H₂O(l)

Explanation:
Decomposition of iron(III) hydroxide.
- 2 Fe(OH)₃ → Fe₂O₃ + 3 H₂O

✔ Balanced

Type: Decomposition

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15. C₄H₁₀(l) + O₂(g) → CO₂(g) + H₂O(g)

This is same as #11.
✔ 2C₄H₁₀(l) + 13O₂(g) → 8CO₂(g) + 10H₂O(g)

Type: Combustion

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Now the word equations (16–20):

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16. dissolved barium chloride + sodium sulfate → barium sulfate (insoluble solid) + dissolved sodium chloride

Chemical Equation:
BaCl₂(aq) + Na₂SO₄(aq) → BaSO₄(s) + 2NaCl(aq)

Balanced: Yes

Type: Double Replacement (precipitation)

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17. calcium metal + dissolved iron(II) nitrate → dissolved calcium nitrate + iron metal

Chemical Equation:
Ca(s) + Fe(NO₃)₂(aq) → Ca(NO₃)₂(aq) + Fe(s)

Balance:
Ca → Ca²⁺, Fe²⁺ → Fe
So:
Ca(s) + Fe(NO₃)₂(aq) → Ca(NO₃)₂(aq) + Fe(s)

But NO₃⁻: left has 2, right has 2 → OK

But charge: Ca²⁺, Fe²⁺ → OK

Wait: Ca(NO₃)₂ needs 2 NO₃⁻ → so Fe(NO₃)₂ has 2 NO₃⁻ → OK

So:
Ca(s) + Fe(NO₃)₂(aq) → Ca(NO₃)₂(aq) + Fe(s)

But this is unbalanced: Ca and Fe are 1:1, but NO₃: 2 on left, 2 on right → yes, balanced!

✔ Ca(s) + Fe(NO₃)₂(aq) → Ca(NO₃)₂(aq) + Fe(s)

Type: Single Replacement

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18. lithium metal + water → dissolved lithium hydroxide + hydrogen gas

Chemical Equation:
2Li(s) + 2H₂O(l) → 2LiOH(aq) + H₂(g)

Balanced: Yes

Type: Single Replacement (or sometimes classified as redox, but standardly single replacement)

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19. dissolved iron(III) hydroxide → iron(III) hydroxide (insoluble solid) + dissolved magnesium nitrate

Wait — this is confusing.

Word equation:
dissolved iron(III) hydroxide → iron(III) hydroxide (insoluble solid) + dissolved magnesium nitrate

That doesn't make sense. Left: dissolved Fe(OH)₃? But Fe(OH)₃ is insoluble.

Likely typo.

Probably meant:
dissolved iron(III) chloride + dissolved magnesium hydroxide → iron(III) hydroxide (insoluble solid) + dissolved magnesium chloride

But given:
"dissolved iron(III) hydroxide" → can't be dissolved, since it's insoluble.

Wait — the actual word equation says:

> dissolved iron(III) hydroxide → iron(III) hydroxide (insoluble solid) + dissolved magnesium nitrate

That's impossible.

Looking again:
19. ____ dissolved iron(III) hydroxide → iron(III) hydroxide (insoluble solid) + dissolved magnesium nitrate

No — that's not logical.

Wait — perhaps it's:

> dissolved iron(III) chloride + dissolved magnesium hydroxide → iron(III) hydroxide (insoluble solid) + dissolved magnesium chloride

Yes, that makes sense.

But the text says:
"____ dissolved iron(III) hydroxide → iron(III) hydroxide (insoluble solid) + dissolved magnesium nitrate"

That can't be.

Wait — actually, the line says:

> 19. ____ dissolved iron(III) hydroxide → iron(III) hydroxide (insoluble solid) + dissolved magnesium nitrate

That's nonsensical.

But looking at your original:

> 19. ____ dissolved iron(III) hydroxide → iron(III) hydroxide (insoluble solid) + dissolved magnesium nitrate

Still wrong.

Wait — maybe it's:

> dissolved iron(III) chloride + dissolved magnesium hydroxide → iron(III) hydroxide (insoluble solid) + dissolved magnesium chloride

But the problem says:

> "dissolved iron(III) hydroxide → iron(III) hydroxide (insoluble solid) + dissolved magnesium nitrate"

This is impossible.

Perhaps it's:

> dissolved iron(III) nitrate + dissolved magnesium hydroxide → iron(III) hydroxide (insoluble solid) + dissolved magnesium nitrate

Yes — that makes sense.

So likely typo: "dissolved iron(III) hydroxide" should be "dissolved iron(III) nitrate"

So corrected:

Fe(NO₃)₃(aq) + Mg(OH)₂(aq) → Fe(OH)₃(s) + Mg(NO₃)₂(aq)

Now balance:

Fe(NO₃)₃ + Mg(OH)₂ → Fe(OH)₃ + Mg(NO₃)₂

Left: Fe=1, NO₃=3, Mg=1, OH=2
Right: Fe=1, OH=3, Mg=1, NO₃=2 → not balanced

Need to balance:

Multiply Fe(NO₃)₃ by 2, Mg(NO₃)₂ by 3?

Try:

2Fe(NO₃)₃ + 3Mg(OH)₂ → 2Fe(OH)₃ + 3Mg(NO₃)₂

Check:
Fe: 2=2
NO₃: 6 left, 6 right
Mg: 3=3
OH: 6 left → 6 right (2Fe(OH)₃ has 6 OH)

Yes!

✔ 2Fe(NO₃)₃(aq) + 3Mg(OH)₂(aq) → 2Fe(OH)₃(s) + 3Mg(NO₃)₂(aq)

Type: Double Replacement (precipitation)

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20. dissolved tin(IV) fluoride + dissolved potassium sulfide → tin(IV) sulfide (insoluble solid) + dissolved potassium fluoride

Chemical Equation:
SnF₄(aq) + K₂S(aq) → SnS₂(s) + 4KF(aq)

Balance:
SnF₄ + K₂S → SnS₂ + KF

SnS₂ has 2 S → need 2 K₂S → 4 K
So: SnF₄ + 2K₂S → SnS₂ + 4KF

Check:
Sn:1=1
F:4=4
K:4=4
S:2=2

✔ Balanced: SnF₄(aq) + 2K₂S(aq) → SnS₂(s) + 4KF(aq)

Type: Double Replacement (precipitation)

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## ✔ Final Answers:

| # | Balanced Equation | Type |
|---|-------------------|------|
| 1 | 2K(s) + Br₂(l) → 2KBr(s) | Synthesis |
| 2 | 4Al(s) + 3O₂(g) → 2Al₂O₃(s) | Synthesis |
| 3 | Cl₂(g) + 2KI(aq) → 2KCl(aq) + I₂(s) | Single Replacement |
| 4 | 3KOH(aq) + H₃PO₄(aq) → K₃PO₄(aq) + 3H₂O(l) | Double Replacement |
| 5 | 4P(s) + 5O₂(g) → 2P₂O₅(g) | Synthesis |
| 6 | 2KClO₃(s) → 2KCl(s) + 3O₂(g) | Decomposition |
| 7 | 3BaCl₂(aq) + 2Na₃PO₄(aq) → 6NaCl(aq) + Ba₃(PO₄)₂(s) | Double Replacement |
| 8 | C₃H₈(g) + 5O₂(g) → 3CO₂(g) + 4H₂O(g) | Combustion |
| 9 | FeS(s) + H₂SO₄(aq) → FeSO₄(aq) + H₂S(g) | Double Replacement *(corrected)* |
| 10 | 2AlBr₃(s) → 2Al(s) + 3Br₂(l) | Decomposition |
| 11 | 2C₄H₁₀(l) + 13O₂(g) → 8CO₂(g) + 10H₂O(g) | Combustion |
| 12 | 2Na(s) + CuCl₂(aq) → 2NaCl(aq) + Cu(s) | Single Replacement |
| 13 | 2K(s) + 2HCl(aq) → 2KCl(aq) + H₂(g) | Single Replacement |
| 14 | 2Fe(OH)₃(s) → Fe₂O₃(s) + 3H₂O(l) | Decomposition |
| 15 | 2C₄H₁₀(l) + 13O₂(g) → 8CO₂(g) + 10H₂O(g) | Combustion |
| 16 | BaCl₂(aq) + Na₂SO₄(aq) → BaSO₄(s) + 2NaCl(aq) | Double Replacement |
| 17 | Ca(s) + Fe(NO₃)₂(aq) → Ca(NO₃)₂(aq) + Fe(s) | Single Replacement |
| 18 | 2Li(s) + 2H₂O(l) → 2LiOH(aq) + H₂(g) | Single Replacement |
| 19 | 2Fe(NO₃)₃(aq) + 3Mg(OH)₂(aq) → 2Fe(OH)₃(s) + 3Mg(NO₃)₂(aq) | Double Replacement |
| 20 | SnF₄(aq) + 2K₂S(aq) → SnS₂(s) + 4KF(aq) | Double Replacement |

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