Free Printable Balancing and Classifying Chemical Equations Worksheets - Free Printable

Here is the complete solution for identifying the type of reaction and balancing each chemical equation from your worksheet.

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(i)

Unbalanced: Na₂CO₃ + HCl → NaCl + H₂CO₃
Type of reaction: Double Displacement (Metathesis)
*Explanation:* Two compounds exchange ions: Na⁺ pairs with Cl⁻, and H⁺ pairs with CO₃²⁻.

Balanced Equation:
Na₂CO₃ + 2HCl → 2NaCl + H₂CO₃
*(Check atoms: Na=2, C=1, O=3, H=2, Cl=2 on both sides)*

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(ii)

Unbalanced: NH₄NO₂ → N₂ + H₂O
Type of reaction: Decomposition
*Explanation:* One compound breaks down into two or more simpler substances. Ammonium nitrite decomposes to nitrogen gas and water.

Balanced Equation:
NH₄NO₂ → N₂ + 2H₂O
*(N=2, H=4, O=2 on both sides)*

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(iii)

Unbalanced: N₂ + O₂ → N₂O₅
Type of reaction: Synthesis (Combination)
*Explanation:* Two elements combine to form a single compound.

Balanced Equation:
2N₂ + 5O₂ → 2N₂O₅
*(N=4, O=10 on both sides)*

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(iv)

Unbalanced: MgCO₃ → MgO + CO₂
Type of reaction: Decomposition
*Explanation:* A single compound breaks down into two products — magnesium oxide and carbon dioxide.

Balanced Equation:
MgCO₃ → MgO + CO₂
*(Already balanced: Mg=1, C=1, O=3 on both sides)*

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(v)

Unbalanced: KBr + Cl₂ → KCl + Br₂
Type of reaction: Single Displacement (Replacement)
*Explanation:* Chlorine (more reactive halogen) displaces bromide from potassium bromide.

Balanced Equation:
2KBr + Cl₂ → 2KCl + Br₂
*(K=2, Br=2, Cl=2 on both sides)*

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(vi)

Unbalanced: Zn + CuSO₄ → Cu + ZnSO₄
Type of reaction: Single Displacement (Replacement)
*Explanation:* Zinc (more reactive metal) displaces copper from copper sulfate.

Balanced Equation:
Zn + CuSO₄ → Cu + ZnSO₄
*(Already balanced: Zn=1, Cu=1, S=1, O=4 on both sides)*

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(vii)

Unbalanced: P + O₂ → P₄O₆
Type of reaction: Synthesis (Combination)
*Explanation:* Phosphorus and oxygen combine to form tetraphosphorus hexoxide.

Balanced Equation:
4P + 3O₂ → P₄O₆
*(P=4, O=6 on both sides)*

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(viii)

Unbalanced: SrBr₂ + (NH₄)₂CO₃ → SrCO₃ + NH₄Br
Type of reaction: Double Displacement (Metathesis)
*Explanation:* Ions swap partners: Sr²⁺ with CO₃²⁻, and NH₄⁺ with Br⁻.

Balanced Equation:
SrBr₂ + (NH₄)₂CO₃ → SrCO₃ + 2NH₄Br
*(Sr=1, Br=2, N=2, H=8, C=1, O=3 on both sides)*

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(ix)

Unbalanced: AgNO₃ + (NH₄)₂CrO₄ → Ag₂CrO₄ + NH₄NO₃
Type of reaction: Double Displacement (Metathesis)
*Explanation:* Silver and ammonium ions switch partners.

Balanced Equation:
2AgNO₃ + (NH₄)₂CrO₄ → Ag₂CrO₄ + 2NH₄NO₃
*(Ag=2, N=4, O=10, Cr=1, H=8 on both sides)*

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(x)

Unbalanced: K + H₂O → KOH + H₂
Type of reaction: Single Displacement (Replacement)
*Explanation:* Potassium displaces hydrogen from water, forming potassium hydroxide and hydrogen gas.

Balanced Equation:
2K + 2H₂O → 2KOH + H₂
*(K=2, H=4, O=2 on both sides)*

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(xi)

Unbalanced: Al + Pb₂(NO₃)₂ → Al(NO₃)₃ + Pb
Type of reaction: Single Displacement (Replacement)
*Explanation:* Aluminum displaces lead from lead(II) nitrate.

Balanced Equation:
2Al + 3Pb₂(NO₃)₂ → 2Al(NO₃)₃ + 6Pb
*(Al=2, Pb=6, N=6, O=18 on both sides)*
> *Note: The formula Pb₂(NO₃)₂ is incorrect — it should be Pb(NO₃)₂. But since the worksheet gives Pb₂(NO₃)₂, we balance accordingly. In reality, lead(II) nitrate is Pb(NO₃)₂, so if corrected, the balanced equation would be:
2Al + 3Pb(NO₃)₂ → 2Al(NO₃)₃ + 3Pb — but per worksheet, we use given formula.*

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(xii)

Unbalanced: Fe + O₂ → Fe₃O₄
Type of reaction: Synthesis (Combination)
*Explanation:* Iron and oxygen combine to form magnetite (Fe₃O₄).

Balanced Equation:
3Fe + 2O₂ → Fe₃O₄
*(Fe=3, O=4 on both sides)*

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## ✔ Final Answer Summary:

| # | Balanced Equation | Type of Reaction |
|---|---------------------------------------------|------------------------------|
| i | Na₂CO₃ + 2HCl → 2NaCl + H₂CO₃ | Double Displacement |
| ii | NH₄NO₂ → N₂ + 2H₂O | Decomposition |
| iii | 2N₂ + 5O₂ → 2N₂O₅ | Synthesis |
| iv | MgCO₃ → MgO + CO₂ | Decomposition |
| v | 2KBr + Cl₂ → 2KCl + Br₂ | Single Displacement |
| vi | Zn + CuSO₄ → Cu + ZnSO₄ | Single Displacement |
| vii | 4P + 3O₂ → P₄O₆ | Synthesis |
| viii| SrBr₂ + (NH₄)₂CO₃ → SrCO₃ + 2NH₄Br | Double Displacement |
| ix | 2AgNO₃ + (NH₄)₂CrO₄ → Ag₂CrO₄ + 2NH₄NO₃ | Double Displacement |
| x | 2K + 2H₂O → 2KOH + H₂ | Single Displacement |
| xi | 2Al + 3Pb₂(NO₃)₂ → 2Al(NO₃)₃ + 6Pb | Single Displacement |
| xii | 3Fe + 2O₂ → Fe₃O₄ | Synthesis |

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📌 Note on (xi): The formula `Pb₂(NO₃)₂` is chemically incorrect. Lead(II) nitrate is correctly written as Pb(NO₃)₂. If you were to correct it, the balanced equation becomes:
2Al + 3Pb(NO₃)₂ → 2Al(NO₃)₃ + 3Pb

But since the worksheet provided `Pb₂(NO₃)₂`, we balanced it as written.

Let me know if you want the corrected version or explanations for any specific reaction!