Worksheet on chemical reactions and chemical equations.

Here's the complete solution to Section 1: Identify the type of reaction from your worksheet.

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🔍 Key Definitions for Reference:

- Synthesis (Combination): Two or more substances combine to form one product.
*A + B → AB*

- Decomposition: One compound breaks down into two or more simpler substances.
*AB → A + B*

- Combustion: A substance reacts with oxygen, usually producing heat and light; hydrocarbons produce CO₂ and H₂O.
*Fuel + O₂ → CO₂ + H₂O*

- Single Displacement (Replacement): One element replaces another in a compound.
*A + BC → AC + B*

- Double Displacement (Metathesis): Ions from two compounds switch partners.
*AB + CD → AD + CB*

- Acid-Base Reaction: A specific type of double displacement where an acid and a base react to form salt and water.
*Acid + Base → Salt + Water*

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## ✔ SOLUTIONS:

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1) Na₃PO₄ + 3 KOH → 3 NaOH + K₃PO₄

→ Double Displacement
*Explanation:* The cations (Na⁺ and K⁺) swap anions (PO₄³⁻ and OH⁻). No combustion, no decomposition, not single displacement — ions just switch partners.

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2) MgCl₂ + Li₂CO₃ → MgCO₃ + 2 LiCl

→ Double Displacement
*Explanation:* Mg²⁺ pairs with CO₃²⁻, Li⁺ pairs with Cl⁻. Classic ion swapping.

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3) C₆H₁₂ + 9 O₂ → 6 CO₂ + 6 H₂O

→ Combustion
*Explanation:* Hydrocarbon reacting with oxygen to produce carbon dioxide and water — textbook combustion.

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4) Pb + FeSO₄ → PbSO₄ + Fe

→ Single Displacement
*Explanation:* Lead (Pb) displaces iron (Fe) from FeSO₄. Pb is more reactive than Fe here (in activity series), so it replaces Fe.

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5) CaCO₃ → CaO + CO₂

→ Decomposition
*Explanation:* One compound (calcium carbonate) breaks down into two products (calcium oxide and carbon dioxide).

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6) P₄ + 3 O₂ → 2 P₂O₃

→ Synthesis
*Explanation:* Phosphorus and oxygen combine to form one product — phosphorus trioxide. Multiple reactants → one product.

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7) 2 RbNO₃ + BeF₂ → Be(NO₃)₂ + 2 RbF

→ Double Displacement
*Explanation:* Rb⁺ swaps with Be²⁺ — nitrate and fluoride ions switch partners.

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8) 2 AgNO₃ + Cu → Cu(NO₃)₂ + 2 Ag

→ Single Displacement
*Explanation:* Copper (Cu) displaces silver (Ag) from silver nitrate — common lab reaction.

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9) C₃H₆O + 4 O₂ → 3 CO₂ + 3 H₂O

→ Combustion
*Explanation:* Organic compound (likely acetone or similar) burns in oxygen to give CO₂ and H₂O — classic combustion.

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10) 2 C₅H₅ + Fe → Fe(C₅H₅)₂

→ Synthesis
*Explanation:* Iron combines with two cyclopentadienyl groups to form ferrocene — one product from multiple reactants.

*(Note: C₅H₅ is cyclopentadienyl radical — this is a coordination compound formation, but still fits synthesis category for high school level.)*

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11) SeCl₆ + O₂ → SeO₂ + 3 Cl₂

→ Single Displacement? — Actually, Not Standard
*Wait — let’s analyze:*

This reaction doesn’t fit neatly into standard categories. Oxygen is displacing chlorine? But O₂ isn’t typically a displacer like metals. In reality, this looks like a redox decomposition or unusual displacement, but since O₂ is not replacing one atom in a typical way, and SeCl₆ is breaking apart, it might be considered decomposition with oxidation.

However, for educational purposes at this level, since O₂ is causing Cl to be released as Cl₂, and Se is oxidized, it’s often classified as a single displacement (oxygen displacing chlorine) — though technically inaccurate chemically.

✔ Best fit for worksheet: Single Displacement
*(Though note: This is a tricky one — some curricula may call it “redox” or “not standard”, but single displacement is the closest match.)*

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12) 2 MgI₂ + Mn(SO₃)₂ → 2 MgSO₃ + MnI₄

→ Double Displacement
*Explanation:* Mg²⁺ pairs with SO₃²⁻, Mn⁴⁺ pairs with I⁻. Ions swap partners.

*(Note: MnI₄ is unusual — manganese(IV) iodide — but assuming it’s written correctly, the reaction type is still double displacement.)*

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13) O₃ → O + O₂

→ Decomposition
*Explanation:* Ozone breaks down into atomic oxygen and diatomic oxygen — one reactant → two products.

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14) 2 NO₂ → 2 O₂ + N₂

→ Decomposition
*Explanation:* Nitrogen dioxide breaks down into nitrogen gas and oxygen gas — one compound → two elements.

*(Note: This reaction is not thermodynamically favored under normal conditions — but for classification, it’s decomposition.)*

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## 📝 Final Answer Key:

1. Double Displacement
2. Double Displacement
3. Combustion
4. Single Displacement
5. Decomposition
6. Synthesis
7. Double Displacement
8. Single Displacement
9. Combustion
10. Synthesis
11. Single Displacement *(with caveat — see explanation above)*
12. Double Displacement
13. Decomposition
14. Decomposition

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Let me know if you’d like help with Section 2 (predicting products) or balancing equations! 😊