Chemistry worksheet for balancing chemical equations and identifying reaction types.

Absolutely! Let’s solve each reaction step by step, predict the products, write the balanced equations, and explain the reasoning. We’ll handle Single Replacement reactions first, then Double Replacement.

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## 🔹 SINGLE REPLACEMENT REACTIONS

In single replacement (also called single displacement), a more reactive element replaces a less reactive one in a compound. We use the Activity Series for metals and Halogen Reactivity Series for nonmetals.

📌 Example I:

Al (s) + Pb(NO₃)₂ (aq) → ?

- Aluminum is above lead in the activity series → Al can displace Pb.
- Products: Al(NO₃)₃ and Pb
- Balance:
Al + Pb(NO₃)₂ → Al(NO₃)₃ + Pb
→ Not balanced. Need to balance atoms.

✔ Balanced Equation:
2Al (s) + 3Pb(NO₃)₂ (aq) → 2Al(NO₃)₃ (aq) + 3Pb (s)

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📌 Example II:

Cl₂ (g) + CuI₂ (aq) → ?

- Chlorine is more reactive than iodine (halogen reactivity: F > Cl > Br > I)
- Cl₂ will displace I⁻ from CuI₂
- Products: CuCl₂ and I₂

✔ Balanced Equation:
Cl₂ (g) + CuI₂ (aq) → CuCl₂ (aq) + I₂ (s)
*(Note: I₂ may precipitate as solid or dissolve slightly — we’ll denote it as (s) for clarity)*

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📌 Example III:

Ag (s) + Ca(IO₃)₂ (aq) → ?

- Silver is below calcium in the activity series → Ag cannot displace Ca²⁺
- NO REACTION

✔ Answer: No Reaction

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1. Zn (s) + CuSO₄ (aq) → ?

- Zinc is above copper → Zn displaces Cu²⁺
- Products: ZnSO₄ and Cu

✔ Balanced Equation:
Zn (s) + CuSO₄ (aq) → ZnSO₄ (aq) + Cu (s)

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2. Cl₂ (g) + KI (aq) → ?

- Cl₂ is more reactive than I₂ → displaces I⁻
- Products: KCl and I₂

✔ Balanced Equation:
Cl₂ (g) + 2KI (aq) → 2KCl (aq) + I₂ (s)

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3. Ni (s) + MgSO₄ (aq) → ?

- Nickel is below magnesium in activity series → Ni cannot displace Mg²⁺
- NO REACTION

✔ Answer: No Reaction

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4. Br₂ (aq) + CaCl₂ (aq) → ?

- Bromine is less reactive than chlorine → cannot displace Cl⁻
- NO REACTION

✔ Answer: No Reaction

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5. F₂ (aq) + ZrCl₄ (s) → ?

- Fluorine is the most reactive halogen → will displace Cl⁻
- Products: ZrF₄ and Cl₂
- Note: ZrCl₄ is solid, but F₂ is very reactive — reaction proceeds.

✔ Balanced Equation:
2F₂ (g) + ZrCl₄ (s) → ZrF₄ (s) + 2Cl₂ (g)
*(We assume F₂ is gas; if aqueous, still reacts vigorously)*

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## 🔹 DOUBLE REPLACEMENT REACTIONS

In double replacement, ions swap partners. Reaction occurs only if a precipitate, gas, or weak electrolyte (like water) forms.

General form: AB + CD → AD + CB

We’ll use solubility rules:

- All nitrates are soluble.
- All alkali metal salts are soluble.
- Sulfates are soluble (except Ba, Sr, Pb, Ca).
- Halides are soluble (except Ag, Pb, Hg).
- Carbonates, phosphates, sulfides, hydroxides are generally insoluble (except with alkali metals or NH₄⁺).

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📌 Example IV:

AlBr₃ (aq) + NaOH (aq) → ?

- Swap: Al³⁺ with OH⁻ → Al(OH)₃ (insoluble precipitate)
- Na⁺ with Br⁻ → NaBr (soluble)

✔ Balanced Equation:
AlBr₃ (aq) + 3NaOH (aq) → Al(OH)₃ (s) + 3NaBr (aq)

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📌 Example V:

BaCl₂ (aq) + K₂SO₄ (aq) → ?

- Ba²⁺ + SO₄²⁻ → BaSO₄ (insoluble precipitate)
- K⁺ + Cl⁻ → KCl (soluble)

✔ Balanced Equation:
BaCl₂ (aq) + K₂SO₄ (aq) → BaSO₄ (s) + 2KCl (aq)

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📌 Example VI:

(NH₄)₂S (s) + LiC₂H₃O₂ (aq) → ?

- (NH₄)₂S is solid? Unusual — typically aqueous. But even if solid, mixing with aqueous LiC₂H₃O₂:
- Possible products: NH₄C₂H₃O₂ and Li₂S
- Both are soluble → NO PRECIPITATE
- Also, no gas or water formed → NO REACTION

✔ Answer: No Reaction

*(Note: If (NH₄)₂S were aqueous, same result — both possible products are soluble.)*

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6. FeCl₂ (aq) + K₂S (aq) → ?

- Fe²⁺ + S²⁻ → FeS (insoluble black precipitate)
- K⁺ + Cl⁻ → KCl (soluble)

✔ Balanced Equation:
FeCl₂ (aq) + K₂S (aq) → FeS (s) + 2KCl (aq)

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7. CuSO₄ (aq) + AgNO₃ (aq) → ?

- Swap: Cu²⁺ with NO₃⁻ → Cu(NO₃)₂ (soluble)
- Ag⁺ with SO₄²⁻ → Ag₂SO₄ (slightly soluble — often considered precipitate)

✔ Balanced Equation:
CuSO₄ (aq) + 2AgNO₃ (aq) → Cu(NO₃)₂ (aq) + Ag₂SO₄ (s)
*(Ag₂SO₄ has low solubility — forms precipitate)*

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8. AlCl₃ (aq) + Na₂CO₃ (aq) → ?

- Al³⁺ + CO₃²⁻ → Al₂(CO₃)₃ → unstable, decomposes to Al(OH)₃ and CO₂ gas!
- Actually, aluminum carbonate hydrolyzes:
2Al³⁺ + 3CO₃²⁻ + 3H₂O → 2Al(OH)₃ (s) + 3CO₂ (g)

✔ Balanced Equation:
2AlCl₃ (aq) + 3Na₂CO₃ (aq) → 2Al(OH)₃ (s) + 3CO₂ (g) + 6NaCl (aq)
*(This is the net result — CO₂ gas drives reaction)*

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9. (NH₄)₂SO₄ (aq) + BaCl₂ (aq) → ?

- Ba²⁺ + SO₄²⁻ → BaSO₄ (s) — precipitate
- NH₄⁺ + Cl⁻ → NH₄Cl (aq) — soluble

✔ Balanced Equation:
(NH₄)₂SO₄ (aq) + BaCl₂ (aq) → BaSO₄ (s) + 2NH₄Cl (aq)

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10. K₃PO₄ (aq) + Fe₂O₃ (s) → ?

- Fe₂O₃ is solid oxide — not ionic in solution → does not dissociate
- Double replacement requires aqueous ionic compounds
- Fe₂O₃ is insoluble and unreactive in this context → NO REACTION

✔ Answer: No Reaction

*(Note: If heated or under special conditions, might react, but not in standard aqueous double replacement.)*

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## ✔ FINAL ANSWERS SUMMARY:

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SINGLE REPLACEMENT:

Example I:
2Al (s) + 3Pb(NO₃)₂ (aq) → 2Al(NO₃)₃ (aq) + 3Pb (s)

Example II:
Cl₂ (g) + CuI₂ (aq) → CuCl₂ (aq) + I₂ (s)

Example III:
No Reaction

1. Zn (s) + CuSO₄ (aq) → ZnSO₄ (aq) + Cu (s)

2. Cl₂ (g) + 2KI (aq) → 2KCl (aq) + I₂ (s)

3. No Reaction

4. No Reaction

5. 2F₂ (g) + ZrCl₄ (s) → ZrF₄ (s) + 2Cl₂ (g)

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DOUBLE REPLACEMENT:

Example IV:
AlBr₃ (aq) + 3NaOH (aq) → Al(OH)₃ (s) + 3NaBr (aq)

Example V:
BaCl₂ (aq) + K₂SO₄ (aq) → BaSO₄ (s) + 2KCl (aq)

Example VI:
No Reaction

6. FeCl₂ (aq) + K₂S (aq) → FeS (s) + 2KCl (aq)

7. CuSO₄ (aq) + 2AgNO₃ (aq) → Cu(NO₃)₂ (aq) + Ag₂SO₄ (s)

8. 2AlCl₃ (aq) + 3Na₂CO₃ (aq) → 2Al(OH)₃ (s) + 3CO₂ (g) + 6NaCl (aq)

9. (NH₄)₂SO₄ (aq) + BaCl₂ (aq) → BaSO₄ (s) + 2NH₄Cl (aq)

10. No Reaction

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Let me know if you’d like the net ionic equations or further explanations!