BALANCING CHEMICAL EQUATIONS WORKSHEETS - Rayness Analytica I ... - Free Printable

Let's solve each of these chemical equations by balancing them. Balancing a chemical equation means ensuring that the number of atoms of each element is the same on both sides (reactants and products), following the Law of Conservation of Mass.

We'll go through each one step by step, showing the balanced equation with coefficients.

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1) ___ N₂ + ___ H₂ → ___ NH₃

Unbalanced: N₂ + H₂ → NH₃
- Nitrogen: 2 on left, 1 on right → need 2 NH₃
- Hydrogen: 2 on left, 3 on right → adjust H₂ to 3

Balanced:
1 N₂ + 3 H₂ → 2 NH₃

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2) ___ KClO₃ → ___ KCl + ___ O₂

Unbalanced: KClO₃ → KCl + O₂
- K: 1 each side ✔
- Cl: 1 each side ✔
- O: 3 on left, 2 on right → LCM of 3 and 2 is 6 → use 2 KClO₃ → 3 O₂

Balanced:
2 KClO₃ → 2 KCl + 3 O₂

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3) ___ NaCl + ___ F₂ → ___ NaF + ___ Cl₂

Unbalanced: NaCl + F₂ → NaF + Cl₂
- Na: 1 each side ✔
- Cl: 1 on left, 2 on right → need 2 NaCl
- F: 2 on left, 1 on right → need 2 NaF

Balanced:
2 NaCl + 1 F₂ → 2 NaF + 1 Cl₂

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4) ___ H₂ + ___ O₂ → ___ H₂O

Unbalanced: H₂ + O₂ → H₂O
- H: 2 on left, 2 on right ✔
- O: 2 on left, 1 on right → need 2 H₂O → then H becomes 4 → need 2 H₂

Balanced:
2 H₂ + 1 O₂ → 2 H₂O

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5) ___ Pb(OH)₂ + ___ HCl → ___ H₂O + ___ PbCl₂

Unbalanced: Pb(OH)₂ + HCl → H₂O + PbCl₂
- Pb: 1 each side ✔
- Cl: 1 on left, 2 on right → need 2 HCl
- H: 2 from OH + 2 from HCl = 4H on left; H₂O has 2H → need 2 H₂O
- O: 2 from OH → 2 H₂O has 2O → OK

Balanced:
1 Pb(OH)₂ + 2 HCl → 2 H₂O + 1 PbCl₂

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6) ___ AlBr₃ + ___ K₂SO₄ → ___ KBr + ___ Al₂(SO₄)₃

Unbalanced: AlBr₃ + K₂SO₄ → KBr + Al₂(SO₄)₃
- Al: 1 on left, 2 on right → need 2 AlBr₃
- SO₄: 1 on left, 3 on right → need 3 K₂SO₄
- K: 2×3=6 on left → need 6 KBr
- Br: 3×2=6 on left → 6 KBr → OK

Balanced:
2 AlBr₃ + 3 K₂SO₄ → 6 KBr + 1 Al₂(SO₄)₃

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7) ___ CH₄ + ___ O₂ → ___ CO₂ + ___ H₂O

Unbalanced: CH₄ + O₂ → CO₂ + H₂O
- C: 1 each side ✔
- H: 4 on left → need 2 H₂O
- O: 2 on left, 2+1=3 on right → need 2 O₂ → 4 O atoms → 2 CO₂? No — only 1 CO₂

Wait:
- CO₂: 1 C → 1 CO₂ ✔
- H₂O: 4H → 2 H₂O ✔
- O: 2 H₂O has 2O, CO₂ has 2O → total 4O → need 2 O₂

Balanced:
1 CH₄ + 2 O₂ → 1 CO₂ + 2 H₂O

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8) ___ C₃H₆ + ___ O₂ → ___ CO₂ + ___ H₂O

Unbalanced: C₃H₆ + O₂ → CO₂ + H₂O
- C: 3 → need 3 CO₂
- H: 6 → need 3 H₂O
- O: Right: 3×2 + 3×1 = 6+3=9 → need 4.5 O₂ → multiply all by 2

Multiply entire equation by 2:
C₆H₁₂ + 9 O₂ → 6 CO₂ + 6 H₂O

But original is C₃H₆ → so better:

Try:
C₃H₆ + O₂ → 3 CO₂ + 3 H₂O
→ O: 3×2 + 3×1 = 6+3=9 → need 4.5 O₂ → not integer

So double:
2 C₃H₆ + 9 O₂ → 6 CO₂ + 6 H₂O

Balanced:
2 C₃H₆ + 9 O₂ → 6 CO₂ + 6 H₂O

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9) ___ C₈H₁₈ + ___ O₂ → ___ CO₂ + ___ H₂O

Octane combustion
- C: 8 → 8 CO₂
- H: 18 → 9 H₂O
- O: Right: 8×2 + 9×1 = 16+9=25 → need 12.5 O₂ → multiply by 2

Double:
2 C₈H₁₈ + 25 O₂ → 16 CO₂ + 18 H₂O

Balanced:
2 C₈H₁₈ + 25 O₂ → 16 CO₂ + 18 H₂O

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10) ___ FeCl₃ + ___ NaOH → ___ Fe(OH)₃ + ___ NaCl

Unbalanced: FeCl₃ + NaOH → Fe(OH)₃ + NaCl
- Fe: 1 each side ✔
- Cl: 3 on left → need 3 NaCl
- Na: 3 on right → need 3 NaOH
- OH: 3 on right → 3 NaOH → OK

Balanced:
1 FeCl₃ + 3 NaOH → 1 Fe(OH)₃ + 3 NaCl

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11) ___ P + ___ O₂ → ___ P₂O₅

Unbalanced: P + O₂ → P₂O₅
- P: 2 on right → need 2 P
- O: 5 on right → need 5/2 O₂ → multiply by 2

Balanced:
4 P + 5 O₂ → 2 P₂O₅

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12) ___ Na + ___ H₂O → ___ NaOH + ___ H₂

Unbalanced: Na + H₂O → NaOH + H₂
- Na: 1 each side ✔
- H: 2 on left, 1 in NaOH + 2 in H₂ → 3H → mismatch

Try:
2 Na + 2 H₂O → 2 NaOH + H₂
- Na: 2 ✔
- H: 4 on left → 2 in NaOH + 2 in H₂ → 4H ✔
- O: 2 on left → 2 in NaOH ✔

Balanced:
2 Na + 2 H₂O → 2 NaOH + 1 H₂

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13) ___ Ag₂O → ___ Ag + ___ O₂

Unbalanced: Ag₂O → Ag + O₂
- Ag: 2 on left → need 2 Ag
- O: 1 on left → 1/2 O₂ → multiply by 2

Balanced:
2 Ag₂O → 4 Ag + 1 O₂

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14) ___ S₈ + ___ O₂ → ___ SO₃

Unbalanced: S₈ + O₂ → SO₃
- S: 8 → need 8 SO₃
- O: 8×3=24 → need 12 O₂

Balanced:
1 S₈ + 12 O₂ → 8 SO₃

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15) ___ CO₂ + ___ H₂O → ___ C₆H₁₂O₆ + ___ O₂

Photosynthesis
- C: 6 → need 6 CO₂
- H: 12 → need 6 H₂O
- O: Left: 6×2 + 6×1 = 12+6=18 → Right: 6 in glucose + 2 O₂ → 6+4=10 → wait

Glucose: C₆H₁₂O₆ → 6 O
O₂: 2 O per molecule

Right: 6 (glucose) + 2×x O₂ → total O = 6 + 2x
Left: 6 CO₂ → 12 O, 6 H₂O → 6 O → total 18 O

So: 6 + 2x = 18 → x = 6

Balanced:
6 CO₂ + 6 H₂O → 1 C₆H₁₂O₆ + 6 O₂

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16) ___ K + ___ MgBr₂ → ___ KBr + ___ Mg

Unbalanced: K + MgBr₂ → KBr + Mg
- Mg: 1 each side ✔
- Br: 2 on left → need 2 KBr
- K: 2 on right → need 2 K

Balanced:
2 K + 1 MgBr₂ → 2 KBr + 1 Mg

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17) ___ HCl + ___ CaCO₃ → ___ CaCl₂ + ___ H₂O + ___ CO₂

Unbalanced: HCl + CaCO₃ → CaCl₂ + H₂O + CO₂
- Ca: 1 each side ✔
- C: 1 each side ✔
- Cl: 2 on right → need 2 HCl
- H: 2 on left → need 1 H₂O
- O: 3 on left → H₂O + CO₂ → 1+2=3 → OK

Balanced:
2 HCl + 1 CaCO₃ → 1 CaCl₂ + 1 H₂O + 1 CO₂

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18) ___ HNO₃ + ___ NaHCO₃ → ___ NaNO₃ + ___ H₂O + ___ CO₂

Unbalanced: HNO₃ + NaHCO₃ → NaNO₃ + H₂O + CO₂
- H: 1+1=2 on left → H₂O needs 2H → OK
- N: 1 each side ✔
- Na: 1 each side ✔
- C: 1 each side ✔
- O: Count? But it’s acid-base reaction → 1:1 ratio

Balanced:
1 HNO₃ + 1 NaHCO₃ → 1 NaNO₃ + 1 H₂O + 1 CO₂

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19) ___ H₂O + ___ O₂ → ___ H₂O₂

Unbalanced: H₂O + O₂ → H₂O₂
- H: 2 on left → 2 on right ✔
- O: 1+2=3 on left → 2 on right → not balanced

Can't balance as written. This is not a standard reaction. Actually, H₂O₂ decomposes, not forms from H₂O and O₂ directly.

But let’s assume we want to form H₂O₂.

Try:
2 H₂O + O₂ → 2 H₂O₂
- H: 4 on left → 4 on right ✔
- O: 2 + 2 = 4 → 4 on right ✔

Balanced:
2 H₂O + 1 O₂ → 2 H₂O₂

(Though this is not thermodynamically favorable.)

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20) ___ NaBr + ___ CaF₂ → ___ NaF + ___ CaBr₂

Unbalanced: NaBr + CaF₂ → NaF + CaBr₂
- Ca: 1 each side ✔
- F: 2 on left → need 2 NaF
- Na: 2 on right → need 2 NaBr
- Br: 2 on right → 2 NaBr → OK

Balanced:
2 NaBr + 1 CaF₂ → 2 NaF + 1 CaBr₂

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21) ___ H₂SO₄ + ___ NaNO₂ → ___ HNO₂ + ___ Na₂SO₄

Unbalanced: H₂SO₄ + NaNO₂ → HNO₂ + Na₂SO₄
- Na: 1 on left → 2 on right → need 2 NaNO₂
- N: 2 on left → 2 HNO₂
- S: 1 each side ✔
- O: check later
- H: 2 on left → 2 HNO₂ → 2H → OK

Now:
H₂SO₄ + 2 NaNO₂ → 2 HNO₂ + Na₂SO₄
- Na: 2 → 2 ✔
- N: 2 → 2 ✔
- S: 1 → 1 ✔
- O: Left: 4 + 2×2 = 4+4=8 → Right: 2×2 + 4 = 4+4=8 ✔
- H: 2 → 2 ✔

Balanced:
1 H₂SO₄ + 2 NaNO₂ → 2 HNO₂ + 1 Na₂SO₄

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✔ Final Balanced Equations:

1) 1 N₂ + 3 H₂ → 2 NH₃
2) 2 KClO₃ → 2 KCl + 3 O₂
3) 2 NaCl + 1 F₂ → 2 NaF + 1 Cl₂
4) 2 H₂ + 1 O₂ → 2 H₂O
5) 1 Pb(OH)₂ + 2 HCl → 2 H₂O + 1 PbCl₂
6) 2 AlBr₃ + 3 K₂SO₄ → 6 KBr + 1 Al₂(SO₄)₃
7) 1 CH₄ + 2 O₂ → 1 CO₂ + 2 H₂O
8) 2 C₃H₆ + 9 O₂ → 6 CO₂ + 6 H₂O
9) 2 C₈H₁₈ + 25 O₂ → 16 CO₂ + 18 H₂O
10) 1 FeCl₃ + 3 NaOH → 1 Fe(OH)₃ + 3 NaCl
11) 4 P + 5 O₂ → 2 P₂O₅
12) 2 Na + 2 H₂O → 2 NaOH + 1 H₂
13) 2 Ag₂O → 4 Ag + 1 O₂
14) 1 S₈ + 12 O₂ → 8 SO₃
15) 6 CO₂ + 6 H₂O → 1 C₆H₁₂O₆ + 6 O₂
16) 2 K + 1 MgBr₂ → 2 KBr + 1 Mg
17) 2 HCl + 1 CaCO₃ → 1 CaCl₂ + 1 H₂O + 1 CO₂
18) 1 HNO₃ + 1 NaHCO₃ → 1 NaNO₃ + 1 H₂O + 1 CO₂
19) 2 H₂O + 1 O₂ → 2 H₂O₂
20) 2 NaBr + 1 CaF₂ → 2 NaF + 1 CaBr₂
21) 1 H₂SO₄ + 2 NaNO₂ → 2 HNO₂ + 1 Na₂SO₄

✔ All equations are now balanced!

Let me know if you'd like these formatted in a table or printed out!