Classifying Chemical Reactions online exercise for - Free Printable

Here is the classification of each chemical reaction as synthesis, decomposition, single replacement, or double replacement, along with a clear explanation for each.

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🔹 1. 2KClO₃ → 2KCl + 3O₂

✔ Decomposition
*Explanation:* One compound (KClO₃) breaks down into two or more simpler substances (KCl and O₂). This is classic decomposition — often seen in thermal decomposition of potassium chlorate.

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🔹 2. HCl + NaOH → NaCl + H₂O

✔ Double Replacement
*Explanation:* The positive ions (H⁺ and Na⁺) swap partners. HCl and NaOH exchange ions to form NaCl and H₂O. Also known as a neutralization reaction, which is a subset of double replacement.

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🔹 3. Mg + 2HCl → MgCl₂ + H₂

✔ Single Replacement
*Explanation:* Magnesium (Mg), a more reactive metal, replaces hydrogen in HCl to form MgCl₂ and releases H₂ gas. A single element replaces another in a compound.

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🔹 4. 2H₂ + O₂ → 2H₂O

✔ Synthesis
*Explanation:* Two elements (H₂ and O₂) combine to form a single compound (H₂O). This is a classic synthesis (or combination) reaction.

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🔹 5. 2Al + 3NiBr₂ → 2AlBr₃ + 3Ni

✔ Single Replacement
*Explanation:* Aluminum (Al) displaces nickel (Ni) from NiBr₂ because Al is more reactive than Ni. One element replaces another in a compound.

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🔹 6. 4Al + 3O₂ → 2Al₂O₃

✔ Synthesis
*Explanation:* Aluminum and oxygen combine to form aluminum oxide. Two elements → one compound = synthesis.

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🔹 7. 2NaCl → 2Na + Cl₂

✔ Decomposition
*Explanation:* Sodium chloride breaks down into its elemental components (Na and Cl₂). This requires electrolysis — still counts as decomposition.

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🔹 8. CaCl₂ + F₂ → CaF₂ + Cl₂

✔ Single Replacement
*Explanation:* Fluorine (F₂), being highly reactive, replaces chlorine in CaCl₂ to form CaF₂ and release Cl₂ gas. Halogens can replace less reactive halogens.

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🔹 9. AgNO₃ + KCl → AgCl + KNO₃

✔ Double Replacement
*Explanation:* Silver and potassium ions swap anions (NO₃⁻ and Cl⁻). Forms a precipitate (AgCl) — classic double replacement.

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🔹 10. N₂ + 3H₂ → 2NH₃

✔ Synthesis
*Explanation:* Nitrogen and hydrogen gases combine to form ammonia. Known as the Haber process — synthesis reaction.

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🔹 11. 2H₂O₂ → 2H₂O + O₂

✔ Decomposition
*Explanation:* Hydrogen peroxide breaks down into water and oxygen. Often catalyzed by MnO₂ — decomposition reaction.

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🔹 12. (NH₄)₂SO₄ + Ba(NO₃)₂ → BaSO₄ + 2NH₄NO₃

✔ Double Replacement
*Explanation:* Ammonium and barium ions swap sulfate and nitrate anions. BaSO₄ is insoluble — forms a precipitate. Classic double replacement.

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🔹 13. MgI₂ + Br₂ → MgBr₂ + I₂

✔ Single Replacement
*Explanation:* Bromine (Br₂), being more reactive than iodine, replaces iodide in MgI₂ to form MgBr₂ and I₂. Halogen displacement.

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🔹 14. SO₃ + H₂O → H₂SO₄

✔ Synthesis
*Explanation:* Sulfur trioxide and water combine to form sulfuric acid. Two compounds → one compound = synthesis.

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🔹 15. 6KCl + Zn₃(PO₄)₂ → 3ZnCl₂ + 2K₃PO₄

✔ Double Replacement
*Explanation:* Potassium and zinc ions swap anions (Cl⁻ and PO₄³⁻). Forms new ionic compounds — double replacement.

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## ✔ Final Answer Summary:

| Reaction # | Type |
|------------|--------------------|
| 1 | Decomposition |
| 2 | Double Replacement |
| 3 | Single Replacement |
| 4 | Synthesis |
| 5 | Single Replacement |
| 6 | Synthesis |
| 7 | Decomposition |
| 8 | Single Replacement |
| 9 | Double Replacement |
| 10 | Synthesis |
| 11 | Decomposition |
| 12 | Double Replacement |
| 13 | Single Replacement |
| 14 | Synthesis |
| 15 | Double Replacement |

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📌 Quick Reference:

- Synthesis: A + B → AB
- Decomposition: AB → A + B
- Single Replacement: A + BC → AC + B
- Double Replacement: AB + CD → AD + CB

Let me know if you’d like balancing practice or net ionic equations for any of these!