Chemistry worksheet focusing on balancing chemical equations and identifying reaction types.
Worksheet for balancing chemical equations and classifying reactions as synthesis, decomposition, single-replacement, or double-replacement.
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Step-by-step solution for: Chemistry: Balancing Chemical Equations Worksheet
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Show Answer Key & Explanations
Step-by-step solution for: Chemistry: Balancing Chemical Equations Worksheet
Let's solve each of these chemical equations step by step. We'll balance the equations and then classify each reaction as synthesis, decomposition, single-replacement, or double-replacement.
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- Antimony (Sb) reacts with chlorine gas to form antimony trichloride.
- Balance: Sb is 1 on both sides, but Cl₂ has 2 atoms, and SbCl₃ needs 3 Cl atoms.
- To balance Cl: use 3 Cl₂ (6 Cl) and 2 SbCl₃ (6 Cl), so need 2 Sb on left.
- Balanced:
2 Sb + 3 Cl₂ → 2 SbCl₃
- Type: Two elements combine to form one compound → Synthesis
✔ Answer:
2 Sb + 3 Cl₂ → 2 SbCl₃ — Synthesis
---
- Magnesium reacts with oxygen to form magnesium oxide.
- O₂ has 2 O atoms, MgO has 1 O per molecule → need 2 MgO.
- So 2 Mg on left.
- Balanced:
2 Mg + O₂ → 2 MgO
- Type: Two elements form one compound → Synthesis
✔ Answer:
2 Mg + O₂ → 2 MgO — Synthesis
---
- Calcium chloride breaks down into calcium metal and chlorine gas.
- CaCl₂ has 1 Ca and 2 Cl → need 1 Ca and 1 Cl₂.
- Balanced:
CaCl₂ → Ca + Cl₂
- Type: One compound breaks into two elements → Decomposition
✔ Answer:
CaCl₂ → Ca + Cl₂ — Decomposition
---
- Sodium chlorate decomposes into sodium chloride and oxygen.
- Left: Na=1, Cl=1, O=3
- Right: Na=1, Cl=1, O=2 in O₂ → not balanced
- Need 3 O atoms → need 3/2 O₂ → multiply entire equation by 2:
- 2 NaClO₃ → 2 NaCl + 3 O₂
- Check: Na=2, Cl=2, O=6 on both sides → balanced
- Type: One compound breaks into two substances → Decomposition
✔ Answer:
2 NaClO₃ → 2 NaCl + 3 O₂ — Decomposition
---
- Iron reacts with hydrochloric acid to produce iron(II) chloride and hydrogen gas.
- FeCl₂ means Fe²⁺, so 2 Cl⁻ needed.
- HCl provides H⁺ and Cl⁻ → need 2 HCl for 2 Cl⁻
- Then H₂ forms from 2 H⁺
- Balanced:
Fe + 2 HCl → FeCl₂ + H₂
- Type: One element replaces another in a compound → Single-replacement
✔ Answer:
Fe + 2 HCl → FeCl₂ + H₂ — Single-replacement
---
- Copper(II) oxide reacts with hydrogen gas to form copper and water.
- CuO → Cu, H₂ → H₂O
- Each H₂O needs 2 H and 1 O → H₂ provides 2 H, CuO provides 1 O
- So 1 CuO + 1 H₂ → 1 Cu + 1 H₂O
- Balanced:
CuO + H₂ → Cu + H₂O
- Type: H₂ replaces Cu in CuO → Single-replacement
✔ Answer:
CuO + H₂ → Cu + H₂O — Single-replacement
---
- Aluminum reacts with sulfuric acid.
- Al₂(SO₄)₃ has 2 Al and 3 SO₄ groups → need 2 Al and 3 H₂SO₄
- 3 H₂SO₄ gives 6 H⁺ → produces 3 H₂ molecules
- Balanced:
2 Al + 3 H₂SO₄ → Al₂(SO₄)₃ + 3 H₂
- Type: Al replaces H → Single-replacement
✔ Answer:
2 Al + 3 H₂SO₄ → Al₂(SO₄)₃ + 3 H₂ — Single-replacement
---
- Magnesium bromide reacts with chlorine gas.
- Cl₂ replaces Br⁻ in MgBr₂ → forms MgCl₂ and Br₂
- MgBr₂ has 2 Br, so Br₂ formed = 1 molecule
- Cl₂ provides 2 Cl → MgCl₂ gets 2 Cl
- Balanced:
MgBr₂ + Cl₂ → MgCl₂ + Br₂
- Type: Cl replaces Br → Single-replacement
✔ Answer:
MgBr₂ + Cl₂ → MgCl₂ + Br₂ — Single-replacement
---
- Tin(IV) oxide reacts with carbon to form tin and carbon monoxide.
- SnO₂ has 2 O atoms → need 2 CO → 2 C atoms
- But C on left → need 2 C
- So: SnO₂ + 2 C → Sn + 2 CO
- Check: Sn=1, O=2, C=2 → yes
- Type: C replaces Sn in oxide → Single-replacement
✔ Answer:
SnO₂ + 2 C → Sn + 2 CO — Single-replacement
---
- Lead(II) nitrate reacts with hydrogen sulfide.
- Pb²⁺ combines with S²⁻ → PbS
- H⁺ combines with NO₃⁻ → HNO₃
- Pb(NO₃)₂ has 2 NO₃⁻ → need 2 HNO₃
- H₂S provides 2 H⁺ → makes 2 HNO₃
- Balanced:
Pb(NO₃)₂ + H₂S → PbS + 2 HNO₃
- Type: Ions swap partners → Double-replacement
✔ Answer:
Pb(NO₃)₂ + H₂S → PbS + 2 HNO₃ — Double-replacement
---
- Mercury(II) oxide decomposes into mercury and oxygen.
- HgO has 1 Hg and 1 O → O₂ needs 2 O → need 2 HgO
- So: 2 HgO → 2 Hg + O₂
- Balanced:
2 HgO → 2 Hg + O₂
- Type: One compound breaks apart → Decomposition
✔ Answer:
2 HgO → 2 Hg + O₂ — Decomposition
---
- Potassium chlorate decomposes.
- Similar to #4: KClO₃ → KCl + O₂
- O₃ → 3 O atoms → need 3/2 O₂ → multiply by 2:
- 2 KClO₃ → 2 KCl + 3 O₂
- Balanced:
2 KClO₃ → 2 KCl + 3 O₂
- Type: Decomposition
✔ Answer:
2 KClO₃ → 2 KCl + 3 O₂ — Decomposition
---
- Nitrogen and hydrogen form ammonia.
- N₂ → 2 N, NH₃ has 1 N → need 2 NH₃
- 2 NH₃ has 6 H → need 3 H₂
- Balanced:
N₂ + 3 H₂ → 2 NH₃
- Type: Two elements form one compound → Synthesis
✔ Answer:
N₂ + 3 H₂ → 2 NH₃ — Synthesis
---
- Sodium bromide reacts with chlorine gas.
- Cl₂ replaces Br⁻ → forms NaCl and Br₂
- Br₂ needs 2 Br → need 2 NaBr
- 2 NaBr → 2 NaCl → need 2 Cl → Cl₂ provides 2 Cl
- Balanced:
2 NaBr + Cl₂ → 2 NaCl + Br₂
- Type: Cl replaces Br → Single-replacement
✔ Answer:
2 NaBr + Cl₂ → 2 NaCl + Br₂ — Single-replacement
---
- Zinc reacts with silver nitrate.
- Zn displaces Ag → forms Zn(NO₃)₂ and Ag
- Zn²⁺ needs 2 NO₃⁻ → need 2 AgNO₃
- 2 AgNO₃ → 2 Ag atoms
- Balanced:
Zn + 2 AgNO₃ → Zn(NO₃)₂ + 2 Ag
- Type: Single replacement
✔ Answer:
Zn + 2 AgNO₃ → Zn(NO₃)₂ + 2 Ag — Single-replacement
---
- Tin reacts with chlorine to form tin(IV) chloride.
- Sn + Cl₂ → SnCl₄ → need 2 Cl₂ for 4 Cl atoms
- Balanced:
Sn + 2 Cl₂ → SnCl₄
- Type: Two elements form one compound → Synthesis
✔ Answer:
Sn + 2 Cl₂ → SnCl₄ — Synthesis
---
- Barium hydroxide decomposes into barium oxide and water.
- Ba(OH)₂ → BaO + H₂O
- Left: Ba=1, O=2, H=2 → right: Ba=1, O=1+1=2, H=2 → balanced
- Balanced:
Ba(OH)₂ → BaO + H₂O
- Type: One compound breaks into two → Decomposition
✔ Answer:
Ba(OH)₂ → BaO + H₂O — Decomposition
---
## ✔ Final Answers:
| # | Balanced Equation | Classification |
|---|-------------------|----------------|
| 1 | 2 Sb + 3 Cl₂ → 2 SbCl₃ | Synthesis |
| 2 | 2 Mg + O₂ → 2 MgO | Synthesis |
| 3 | CaCl₂ → Ca + Cl₂ | Decomposition |
| 4 | 2 NaClO₃ → 2 NaCl + 3 O₂ | Decomposition |
| 5 | Fe + 2 HCl → FeCl₂ + H₂ | Single-replacement |
| 6 | CuO + H₂ → Cu + H₂O | Single-replacement |
| 7 | 2 Al + 3 H₂SO₄ → Al₂(SO₄)₃ + 3 H₂ | Single-replacement |
| 8 | MgBr₂ + Cl₂ → MgCl₂ + Br₂ | Single-replacement |
| 9 | SnO₂ + 2 C → Sn + 2 CO | Single-replacement |
|10 | Pb(NO₃)₂ + H₂S → PbS + 2 HNO₃ | Double-replacement |
|11 | 2 HgO → 2 Hg + O₂ | Decomposition |
|12 | 2 KClO₃ → 2 KCl + 3 O₂ | Decomposition |
|13 | N₂ + 3 H₂ → 2 NH₃ | Synthesis |
|14 | 2 NaBr + Cl₂ → 2 NaCl + Br₂ | Single-replacement |
|15 | Zn + 2 AgNO₃ → Zn(NO₃)₂ + 2 Ag | Single-replacement |
|16 | Sn + 2 Cl₂ → SnCl₄ | Synthesis |
|17 | Ba(OH)₂ → BaO + H₂O | Decomposition |
---
Let me know if you'd like this formatted as a printable PDF or need explanations for any specific steps!
---
1. Sb + Cl₂ → SbCl₃
- Antimony (Sb) reacts with chlorine gas to form antimony trichloride.
- Balance: Sb is 1 on both sides, but Cl₂ has 2 atoms, and SbCl₃ needs 3 Cl atoms.
- To balance Cl: use 3 Cl₂ (6 Cl) and 2 SbCl₃ (6 Cl), so need 2 Sb on left.
- Balanced:
2 Sb + 3 Cl₂ → 2 SbCl₃
- Type: Two elements combine to form one compound → Synthesis
✔ Answer:
2 Sb + 3 Cl₂ → 2 SbCl₃ — Synthesis
---
2. Mg + O₂ → MgO
- Magnesium reacts with oxygen to form magnesium oxide.
- O₂ has 2 O atoms, MgO has 1 O per molecule → need 2 MgO.
- So 2 Mg on left.
- Balanced:
2 Mg + O₂ → 2 MgO
- Type: Two elements form one compound → Synthesis
✔ Answer:
2 Mg + O₂ → 2 MgO — Synthesis
---
3. CaCl₂ → Ca + Cl₂
- Calcium chloride breaks down into calcium metal and chlorine gas.
- CaCl₂ has 1 Ca and 2 Cl → need 1 Ca and 1 Cl₂.
- Balanced:
CaCl₂ → Ca + Cl₂
- Type: One compound breaks into two elements → Decomposition
✔ Answer:
CaCl₂ → Ca + Cl₂ — Decomposition
---
4. NaClO₃ → NaCl + O₂
- Sodium chlorate decomposes into sodium chloride and oxygen.
- Left: Na=1, Cl=1, O=3
- Right: Na=1, Cl=1, O=2 in O₂ → not balanced
- Need 3 O atoms → need 3/2 O₂ → multiply entire equation by 2:
- 2 NaClO₃ → 2 NaCl + 3 O₂
- Check: Na=2, Cl=2, O=6 on both sides → balanced
- Type: One compound breaks into two substances → Decomposition
✔ Answer:
2 NaClO₃ → 2 NaCl + 3 O₂ — Decomposition
---
5. Fe + HCl → FeCl₂ + H₂
- Iron reacts with hydrochloric acid to produce iron(II) chloride and hydrogen gas.
- FeCl₂ means Fe²⁺, so 2 Cl⁻ needed.
- HCl provides H⁺ and Cl⁻ → need 2 HCl for 2 Cl⁻
- Then H₂ forms from 2 H⁺
- Balanced:
Fe + 2 HCl → FeCl₂ + H₂
- Type: One element replaces another in a compound → Single-replacement
✔ Answer:
Fe + 2 HCl → FeCl₂ + H₂ — Single-replacement
---
6. CuO + H₂ → Cu + H₂O
- Copper(II) oxide reacts with hydrogen gas to form copper and water.
- CuO → Cu, H₂ → H₂O
- Each H₂O needs 2 H and 1 O → H₂ provides 2 H, CuO provides 1 O
- So 1 CuO + 1 H₂ → 1 Cu + 1 H₂O
- Balanced:
CuO + H₂ → Cu + H₂O
- Type: H₂ replaces Cu in CuO → Single-replacement
✔ Answer:
CuO + H₂ → Cu + H₂O — Single-replacement
---
7. Al + H₂SO₄ → Al₂(SO₄)₃ + H₂
- Aluminum reacts with sulfuric acid.
- Al₂(SO₄)₃ has 2 Al and 3 SO₄ groups → need 2 Al and 3 H₂SO₄
- 3 H₂SO₄ gives 6 H⁺ → produces 3 H₂ molecules
- Balanced:
2 Al + 3 H₂SO₄ → Al₂(SO₄)₃ + 3 H₂
- Type: Al replaces H → Single-replacement
✔ Answer:
2 Al + 3 H₂SO₄ → Al₂(SO₄)₃ + 3 H₂ — Single-replacement
---
8. MgBr₂ + Cl₂ → MgCl₂ + Br₂
- Magnesium bromide reacts with chlorine gas.
- Cl₂ replaces Br⁻ in MgBr₂ → forms MgCl₂ and Br₂
- MgBr₂ has 2 Br, so Br₂ formed = 1 molecule
- Cl₂ provides 2 Cl → MgCl₂ gets 2 Cl
- Balanced:
MgBr₂ + Cl₂ → MgCl₂ + Br₂
- Type: Cl replaces Br → Single-replacement
✔ Answer:
MgBr₂ + Cl₂ → MgCl₂ + Br₂ — Single-replacement
---
9. SnO₂ + C → Sn + CO
- Tin(IV) oxide reacts with carbon to form tin and carbon monoxide.
- SnO₂ has 2 O atoms → need 2 CO → 2 C atoms
- But C on left → need 2 C
- So: SnO₂ + 2 C → Sn + 2 CO
- Check: Sn=1, O=2, C=2 → yes
- Type: C replaces Sn in oxide → Single-replacement
✔ Answer:
SnO₂ + 2 C → Sn + 2 CO — Single-replacement
---
10. Pb(NO₃)₂ + H₂S → PbS + HNO₃
- Lead(II) nitrate reacts with hydrogen sulfide.
- Pb²⁺ combines with S²⁻ → PbS
- H⁺ combines with NO₃⁻ → HNO₃
- Pb(NO₃)₂ has 2 NO₃⁻ → need 2 HNO₃
- H₂S provides 2 H⁺ → makes 2 HNO₃
- Balanced:
Pb(NO₃)₂ + H₂S → PbS + 2 HNO₃
- Type: Ions swap partners → Double-replacement
✔ Answer:
Pb(NO₃)₂ + H₂S → PbS + 2 HNO₃ — Double-replacement
---
11. HgO → Hg + O₂
- Mercury(II) oxide decomposes into mercury and oxygen.
- HgO has 1 Hg and 1 O → O₂ needs 2 O → need 2 HgO
- So: 2 HgO → 2 Hg + O₂
- Balanced:
2 HgO → 2 Hg + O₂
- Type: One compound breaks apart → Decomposition
✔ Answer:
2 HgO → 2 Hg + O₂ — Decomposition
---
12. KClO₃ → KCl + O₂
- Potassium chlorate decomposes.
- Similar to #4: KClO₃ → KCl + O₂
- O₃ → 3 O atoms → need 3/2 O₂ → multiply by 2:
- 2 KClO₃ → 2 KCl + 3 O₂
- Balanced:
2 KClO₃ → 2 KCl + 3 O₂
- Type: Decomposition
✔ Answer:
2 KClO₃ → 2 KCl + 3 O₂ — Decomposition
---
13. N₂ + H₂ → NH₃
- Nitrogen and hydrogen form ammonia.
- N₂ → 2 N, NH₃ has 1 N → need 2 NH₃
- 2 NH₃ has 6 H → need 3 H₂
- Balanced:
N₂ + 3 H₂ → 2 NH₃
- Type: Two elements form one compound → Synthesis
✔ Answer:
N₂ + 3 H₂ → 2 NH₃ — Synthesis
---
14. NaBr + Cl₂ → NaCl + Br₂
- Sodium bromide reacts with chlorine gas.
- Cl₂ replaces Br⁻ → forms NaCl and Br₂
- Br₂ needs 2 Br → need 2 NaBr
- 2 NaBr → 2 NaCl → need 2 Cl → Cl₂ provides 2 Cl
- Balanced:
2 NaBr + Cl₂ → 2 NaCl + Br₂
- Type: Cl replaces Br → Single-replacement
✔ Answer:
2 NaBr + Cl₂ → 2 NaCl + Br₂ — Single-replacement
---
15. Zn + AgNO₃ → Zn(NO₃)₂ + Ag
- Zinc reacts with silver nitrate.
- Zn displaces Ag → forms Zn(NO₃)₂ and Ag
- Zn²⁺ needs 2 NO₃⁻ → need 2 AgNO₃
- 2 AgNO₃ → 2 Ag atoms
- Balanced:
Zn + 2 AgNO₃ → Zn(NO₃)₂ + 2 Ag
- Type: Single replacement
✔ Answer:
Zn + 2 AgNO₃ → Zn(NO₃)₂ + 2 Ag — Single-replacement
---
16. Sn + Cl₂ → SnCl₄
- Tin reacts with chlorine to form tin(IV) chloride.
- Sn + Cl₂ → SnCl₄ → need 2 Cl₂ for 4 Cl atoms
- Balanced:
Sn + 2 Cl₂ → SnCl₄
- Type: Two elements form one compound → Synthesis
✔ Answer:
Sn + 2 Cl₂ → SnCl₄ — Synthesis
---
17. Ba(OH)₂ → BaO + H₂O
- Barium hydroxide decomposes into barium oxide and water.
- Ba(OH)₂ → BaO + H₂O
- Left: Ba=1, O=2, H=2 → right: Ba=1, O=1+1=2, H=2 → balanced
- Balanced:
Ba(OH)₂ → BaO + H₂O
- Type: One compound breaks into two → Decomposition
✔ Answer:
Ba(OH)₂ → BaO + H₂O — Decomposition
---
## ✔ Final Answers:
| # | Balanced Equation | Classification |
|---|-------------------|----------------|
| 1 | 2 Sb + 3 Cl₂ → 2 SbCl₃ | Synthesis |
| 2 | 2 Mg + O₂ → 2 MgO | Synthesis |
| 3 | CaCl₂ → Ca + Cl₂ | Decomposition |
| 4 | 2 NaClO₃ → 2 NaCl + 3 O₂ | Decomposition |
| 5 | Fe + 2 HCl → FeCl₂ + H₂ | Single-replacement |
| 6 | CuO + H₂ → Cu + H₂O | Single-replacement |
| 7 | 2 Al + 3 H₂SO₄ → Al₂(SO₄)₃ + 3 H₂ | Single-replacement |
| 8 | MgBr₂ + Cl₂ → MgCl₂ + Br₂ | Single-replacement |
| 9 | SnO₂ + 2 C → Sn + 2 CO | Single-replacement |
|10 | Pb(NO₃)₂ + H₂S → PbS + 2 HNO₃ | Double-replacement |
|11 | 2 HgO → 2 Hg + O₂ | Decomposition |
|12 | 2 KClO₃ → 2 KCl + 3 O₂ | Decomposition |
|13 | N₂ + 3 H₂ → 2 NH₃ | Synthesis |
|14 | 2 NaBr + Cl₂ → 2 NaCl + Br₂ | Single-replacement |
|15 | Zn + 2 AgNO₃ → Zn(NO₃)₂ + 2 Ag | Single-replacement |
|16 | Sn + 2 Cl₂ → SnCl₄ | Synthesis |
|17 | Ba(OH)₂ → BaO + H₂O | Decomposition |
---
Let me know if you'd like this formatted as a printable PDF or need explanations for any specific steps!
Parent Tip: Review the logic above to help your child master the concept of chemistry balancing equations worksheet.
![49 Balancing Chemical Equations Worksheets [with Answers]](/images2/chemistry-balancing-equations-worksheet/chemistry-balancing-equations-worksheet-0.jpg)
