Worksheet titled "Balancing Equations Worksheet" featuring 22 chemical equations that need to be balanced, designed for cooperative group practice in chemistry.

Let's go through each of these chemical equations and balance them step by step. Balancing chemical equations means ensuring that the number of atoms of each element is the same on both sides of the equation (conservation of mass).

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1. Ca + O₂ → CaO

- Left: 1 Ca, 2 O
- Right: 1 Ca, 1 O
→ Add 2 CaO on right → now 2 O and 2 Ca
→ Add 2 Ca on left

Balanced:
2Ca + O₂ → 2CaO

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2. H₂ + Cl₂ → HCl

- Left: 2 H, 2 Cl
- Right: 1 H, 1 Cl
→ Add 2 HCl

Balanced:
H₂ + Cl₂ → 2HCl

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3. P₄ + S₈ → P₂S₅

- Left: 4 P, 8 S
- Right: 2 P, 5 S
We need to make P and S match.

Let’s find LCM for P: 4 and 2 → LCM = 4 → use 2P₂S₅ → 4P, 10S
But S₈ has 8 S → need multiple of 8 and 10 → LCM = 40

So:
- Use 5 P₄ → 20 P
- Use 5 S₈ → 40 S
- Right: P₂S₅ → needs 10 P and 25 S per unit → not good.

Try:
- 2P₄ → 8P
- S₈ → 8S
- Product: P₂S₅ → 2P, 5S → so we need multiples.

Let’s try:
- 2P₄ = 8P → need 4 P₂S₅ (since each has 2P) → 4×P₂S₅ = 8P, 20S
- So need 20 S → S₈ has 8 S → 20/8 = 2.5 → not integer.

Try:
- 5P₄ = 20P → need 10 P₂S₅ → 20P, 50S
- S₈ → 50S → 50/8 = 6.25 → no

Wait — maybe formula is wrong? But assuming it's correct.

Try:
- Let’s suppose: aP₄ + bS₈ → cP₂S₅
- P: 4a = 2c → 2a = c
- S: 8b = 5c → substitute c = 2a → 8b = 10a → 4b = 5a → a = 4k, b = 5k, c = 8k

So smallest k=1 → a=4, b=5, c=8

Balanced:
4P₄ + 5S₈ → 8P₂S₅

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4. CO + O₂ → CO₂

- Left: 1 C, 1 O (from CO) + 2 O (from O₂) = total 3 O, 1 C
- Right: 1 C, 2 O
→ Not balanced.

Try:
- 2CO + O₂ → 2CO₂
Left: 2C, 2O + 2O = 4O
Right: 2C, 4O → yes!

Balanced:
2CO + O₂ → 2CO₂

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5. C₂H₆ + O₂ → CO₂ + H₂O

- Left: 2C, 6H, 2O
- Right: 1C, 2H, 3O (in CO₂ and H₂O)

Balance C: 2CO₂
Balance H: 6H → 3H₂O
Now right: 2C, 6H, 2×2 + 3×1 = 4+3 = 7O
Left: O₂ → need 7/2 = 3.5 → multiply all by 2:

→ 2C₂H₆ + 7O₂ → 4CO₂ + 6H₂O

Check:
- Left: 4C, 12H, 14O
- Right: 4C, 12H, 8O (CO₂) + 6O (H₂O) = 14O → yes

Balanced:
2C₂H₆ + 7O₂ → 4CO₂ + 6H₂O

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6. C₂H₅OH + O₂ → CO₂ + H₂O

- C₂H₅OH = 2C, 6H, 1O
- Balance C: 2CO₂
- H: 6H → 3H₂O
- Right: 2CO₂ + 3H₂O → 2C, 6H, 4O + 3O = 7O
- Left: C₂H₅OH has 1O, so O₂ must supply 6O → 3O₂

So:
C₂H₅OH + 3O₂ → 2CO₂ + 3H₂O

Check:
- Left: 2C, 6H, 1O + 6O = 7O
- Right: 2C, 6H, 4O + 3O = 7O → yes

Balanced:
C₂H₅OH + 3O₂ → 2CO₂ + 3H₂O

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7. FeS₂ + O₂ → Fe₂O₃ + SO₂

- Left: 1Fe, 2S, 2O
- Right: 2Fe, 3O, 1S → not balanced

Let’s balance:
- Fe: 2FeS₂ → 2Fe
- S: 2FeS₂ → 4S → need 4SO₂
- O: 4SO₂ has 8O, Fe₂O₃ has 3O → total 11O
- O₂ provides 2O per molecule → need 11/2 = 5.5 → ×2

So:
- 4FeS₂ → 4Fe, 8S → 4SO₂ ×2 = 8SO₂? Wait.

Start over:

Let’s say:
aFeS₂ + bO₂ → cFe₂O₃ + dSO₂

Fe: a = 2c
S: 2a = d
O: 2b = 3c + 2d

Substitute:
From a = 2c → c = a/2
d = 2a
Then O: 2b = 3(a/2) + 2(2a) = (3a/2) + 4a = (3a + 8a)/2 = 11a/2
So 2b = 11a/2 → b = 11a/4

To eliminate fractions, let a = 4 → then:
- a = 4 → FeS₂ = 4
- c = 2 → Fe₂O₃ = 2
- d = 8 → SO₂ = 8
- b = 11 → O₂ = 11

Check:
Left: 4FeS₂ → 4Fe, 8S; 11O₂ → 22O
Right: 2Fe₂O₃ → 4Fe, 6O; 8SO₂ → 8S, 16O → total 4Fe, 8S, 22O → perfect

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

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8. P₄ + O₃ → P₂O₅

- P₄ → 4P
- P₂O₅ → 2P → so need 2P₂O₅ → 4P, 10O
- O₃ → 3O → need 10/3 → not integer

Try:
aP₄ + bO₃ → cP₂O₅
P: 4a = 2c → 2a = c
O: 3b = 5c → 3b = 5(2a) = 10a → b = (10/3)a

Set a = 3 → b = 10, c = 6

So:
3P₄ + 10O₃ → 6P₂O₅

Check:
- Left: 12P, 30O
- Right: 12P, 30O → yes

Balanced:
3P₄ + 10O₃ → 6P₂O₅

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9. NH₃ + O₂ → N₂O₃ + H₂O

- Left: N, 3H, 2O
- Right: 2N, 3O, 2H

Balance N: 2NH₃ → 2N
H: 6H → 3H₂O
O: Right: N₂O₃ has 3O, 3H₂O has 3O → total 6O
Left: O₂ → 3O₂ → 6O

So:
2NH₃ + 3O₂ → N₂O₃ + 3H₂O

Check:
- Left: 2N, 6H, 6O
- Right: 2N, 3O (N₂O₃) + 3O (H₂O) = 6O, 6H → yes

Balanced:
2NH₃ + 3O₂ → N₂O₃ + 3H₂O

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10. Si₅H₁₁ + Br₂ → Si + HBr

- Left: 5Si, 11H, 2Br
- Right: Si, H, Br

Balance Si: 5Si
H: 11H → 11HBr
Br: 11Br → need 11/2 Br₂ → 5.5 → ×2

So:
2Si₅H₁₁ + 11Br₂ → 10Si + 22HBr

Check:
- Left: 10Si, 22H, 22Br
- Right: 10Si, 22H, 22Br → yes

Balanced:
2Si₅H₁₁ + 11Br₂ → 10Si + 22HBr

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11. FeCl₃ + NaOH → Fe(OH)₃ + NaCl

- Left: Fe, 3Cl, Na, O, H
- Right: Fe, 3O, 3H, Na, Cl

Balance Fe: 1:1
Cl: 3 on left → need 3NaCl
Na: 3Na → need 3NaOH
OH: 3NaOH → 3OH → Fe(OH)₃ → matches

So:
FeCl₃ + 3NaOH → Fe(OH)₃ + 3NaCl

Check: All atoms match.

Balanced:
FeCl₃ + 3NaOH → Fe(OH)₃ + 3NaCl

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12. Fe + H₂O → Fe₂O₃ + H₂

- Left: Fe, 2H, 1O
- Right: 2Fe, 3O, 2H

Balance Fe: 2Fe
O: 3O → need 3H₂O
H: 6H → 3H₂

So:
2Fe + 3H₂O → Fe₂O₃ + 3H₂

Check:
- Left: 2Fe, 6H, 3O
- Right: 2Fe, 3O, 6H → yes

Balanced:
2Fe + 3H₂O → Fe₂O₃ + 3H₂

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13. C₁₀H₂₂ + Cl₂ → C + HCl

- Left: 10C, 22H, 2Cl
- Right: C, H, Cl

Balance C: 10C
H: 22H → 22HCl
Cl: 22Cl → 11Cl₂

So:
C₁₀H₂₂ + 11Cl₂ → 10C + 22HCl

Check: Yes

Balanced:
C₁₀H₂₂ + 11Cl₂ → 10C + 22HCl

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14. FeCl₃ + Na₂SO₄ → Fe₂(SO₄)₃ + NaCl

- Left: Fe, 3Cl, 2Na, S, 4O
- Right: 2Fe, 3S, 12O, Na, Cl

Balance Fe: 2FeCl₃
SO₄: 3SO₄ → 3Na₂SO₄
Na: 6Na → 6NaCl
Cl: 6Cl → 6NaCl

So:
2FeCl₃ + 3Na₂SO₄ → Fe₂(SO₄)₃ + 6NaCl

Check:
- Left: 2Fe, 6Cl, 6Na, 3S, 12O
- Right: 2Fe, 3S, 12O, 6Na, 6Cl → yes

Balanced:
2FeCl₃ + 3Na₂SO₄ → Fe₂(SO₄)₃ + 6NaCl

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15. Al + HNO₃ → Al(NO₃)₃ + H₂

- Left: Al, H, N, O
- Right: Al, 3N, 9O, 2H

Al: 1:1
NO₃: 3 → need 3HNO₃
H: 3H → but H₂ has 2H → problem

3H → 1.5H₂ → ×2

So:
2Al + 6HNO₃ → 2Al(NO₃)₃ + 3H₂

Check:
- Left: 2Al, 6H, 6N, 18O
- Right: 2Al, 6N, 18O, 6H → yes

Balanced:
2Al + 6HNO₃ → 2Al(NO₃)₃ + 3H₂

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16. K + H₂O → KOH + H₂

- Left: K, 2H, 1O
- Right: K, O, H, H₂

Balance K: 1:1
H: 2H on left → 1H in KOH, 2H in H₂ → total 3H → mismatch

Try:
2K + 2H₂O → 2KOH + H₂

Left: 2K, 4H, 2O
Right: 2K, 2O, 2H (in KOH), 2H (in H₂) → 4H → yes

Balanced:
2K + 2H₂O → 2KOH + H₂

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17. C₃H₈ + S₈ → CS₂ + H₂S

- Left: 3C, 8H, 8S
- Right: C, 2S, 2H, S → CS₂ and H₂S

Balance C: 3CS₂ → 3C, 6S
H: 8H → 4H₂S → 4S
Total S: 6 + 4 = 10S → need 10S → S₈ → 10/8 = 1.25 → ×4

So:
4C₃H₈ + 5S₈ → 12CS₂ + 16H₂S

Check:
- Left: 12C, 32H, 40S
- Right: 12C, 24S (CS₂), 16S (H₂S) = 40S, 32H → yes

Balanced:
4C₃H₈ + 5S₈ → 12CS₂ + 16H₂S

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18. MgCl₂ + Al(OH)₃ → AlCl₃ + Mg(OH)₂

- Left: Mg, 2Cl, Al, 3O, 3H
- Right: Al, 3Cl, Mg, 2O, 2H

Balance Cl: 3 on right → need 3MgCl₂ → 3Cl
But MgCl₂ has 2Cl → 3MgCl₂ → 6Cl → need 2AlCl₃ → 6Cl

So:
3MgCl₂ + 2Al(OH)₃ → 2AlCl₃ + 3Mg(OH)₂

Check:
- Left: 3Mg, 6Cl, 2Al, 6O, 6H
- Right: 2Al, 6Cl, 3Mg, 6O, 6H → yes

Balanced:
3MgCl₂ + 2Al(OH)₃ → 2AlCl₃ + 3Mg(OH)₂

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19. ZnFeS₂ + O₂ → Zn + FeO + SO₂

- Left: Zn, Fe, 2S, 2O
- Right: Zn, Fe, O, S, O

Balance Zn: 1:1
Fe: 1:1
S: 2 → 2SO₂
O: 2SO₂ has 4O, FeO has 1O → total 5O → need 2.5O₂ → ×2

So:
2ZnFeS₂ + 5O₂ → 2Zn + 2FeO + 4SO₂

Check:
- Left: 2Zn, 2Fe, 4S, 10O
- Right: 2Zn, 2Fe, 2O (FeO), 8O (SO₂) = 10O, 4S → yes

Balanced:
2ZnFeS₂ + 5O₂ → 2Zn + 2FeO + 4SO₂

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20. P₄O₁₀ + H₂O → H₃PO₄

- Left: 4P, 10O + 1O = 11O, 2H
- Right: H₃PO₄ → 3H, 1P, 4O

Balance P: 4H₃PO₄ → 4P, 12H, 16O
Left: P₄O₁₀ → 4P, 10O → need 6 more O → 6H₂O → 6O, 12H

So:
P₄O₁₀ + 6H₂O → 4H₃PO₄

Check:
- Left: 4P, 10O + 6O = 16O, 12H
- Right: 4P, 16O, 12H → yes

Balanced:
P₄O₁₀ + 6H₂O → 4H₃PO₄

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21. KClO₃ → KCl + KClO₄

- This is a decomposition.
- Left: K, Cl, 3O
- Right: KCl: K, Cl; KClO₄: K, Cl, 4O → total 2K, 2Cl, 4O → not matching

Try:
2KClO₃ → KCl + KClO₄

Left: 2K, 2Cl, 6O
Right: KCl: K, Cl; KClO₄: K, Cl, 4O → total 2K, 2Cl, 4O → 2O missing

No — perhaps:
3KClO₃ → KCl + 2KClO₄?

Left: 3K, 3Cl, 9O
Right: KCl: 1K,1Cl; 2KClO₄: 2K,2Cl,8O → total 3K,3Cl,8O → 1O short

Try:
4KClO₃ → KCl + 3KClO₄
Left: 4K,4Cl,12O
Right: 1K,1Cl + 3K,3Cl,12O → 4K,4Cl,12O → yes!

Balanced:
4KClO₃ → KCl + 3KClO₄

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22. Mg₃N₂ + H₂O → Mg(OH)₂ + NH₃

- Left: 3Mg, 2N, 2H, 1O
- Right: Mg, 2O, 2H, N, 3H → NH₃ has 3H

Balance Mg: 3Mg → 3Mg(OH)₂
N: 2N → 2NH₃
H: 3Mg(OH)₂ → 6H, 2NH₃ → 6H → total 12H
O: 3Mg(OH)₂ → 6O → need 6H₂O → 12H, 6O

So:
Mg₃N₂ + 6H₂O → 3Mg(OH)₂ + 2NH₃

Check:
- Left: 3Mg, 2N, 12H, 6O
- Right: 3Mg, 6O, 6H (from OH), 6H (from NH₃) = 12H, 2N → yes

Balanced:
Mg₃N₂ + 6H₂O → 3Mg(OH)₂ + 2NH₃

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✔ Final Answers:

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

Let me know if you'd like this in a printable format or with explanations for any specific one!