Balancing Chemical Equations Practice Sheet - Free Printable
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Step-by-step solution for: Balancing Chemical Equations Practice Sheet
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Show Answer Key & Explanations
Step-by-step solution for: Balancing Chemical Equations Practice Sheet
To balance chemical equations, we need to ensure that the number of atoms of each element is the same on both sides of the equation. Here are the balanced equations for each problem:
---
- Start by balancing the potassium (K) atoms:
- There are 3 K atoms in K₃PO₄, so we need 3 KOH molecules.
- Now balance the phosphorus (P) atoms:
- There is 1 P atom in H₃PO₄ and 1 P atom in K₃PO₄, so H₃PO₄ is already balanced.
- Balance the hydrogen (H) atoms:
- On the left, 3 KOH provides 3 H atoms, and H₃PO₄ provides 3 more H atoms, totaling 6 H atoms.
- On the right, H₂O needs 2 H atoms per molecule, so we need 3 H₂O molecules.
- Finally, check oxygen (O):
- On the left, H₃PO₄ has 4 O atoms.
- On the right, K₃PO₄ has 4 O atoms, and 3 H₂O provides 3 O atoms, totaling 7 O atoms. This is balanced.
Balanced Equation:
$$
\boxed{3 \text{ KOH} + 1 \text{ H}_3\text{PO}_4 \rightarrow 1 \text{ K}_3\text{PO}_4 + 3 \text{ H}_2\text{O}}
$$
---
- Balance nitrogen (N) atoms:
- There is 1 N atom in NH₃ and 1 N atom in NO, so NH₃ is already balanced.
- Balance hydrogen (H) atoms:
- NH₃ provides 3 H atoms, so we need 3/2 H₂O molecules. To avoid fractions, multiply everything by 2.
- Balance oxygen (O) atoms:
- After multiplying by 2, we have 2 NH₃ → 2 NO + 3 H₂O. Now, there are 2 O atoms in 2 NO and 3 O atoms in 3 H₂O, totaling 5 O atoms. We need 5/2 O₂ molecules, so multiply by 2 again.
- Final balanced equation:
$$
\boxed{4 \text{ NH}_3 + 5 \text{ O}_2 \rightarrow 4 \text{ NO} + 6 \text{ H}_2\text{O}}
$$
---
- Balance aluminum (Al) atoms:
- There are 2 Al atoms in Al₂O₃, so we need 2 Al atoms on the left.
- Balance oxygen (O) atoms:
- There are 3 O atoms in Al₂O₃, so we need 3/2 O₂ molecules. Multiply everything by 2 to avoid fractions.
$$
\boxed{4 \text{ Al} + 3 \text{ O}_2 \rightarrow 2 \text{ Al}_2\text{O}_3}
$$
---
- Balance calcium (Ca) atoms:
- There are 2 Ca atoms on the right (1 in Ca(HS)₂ and 1 in Ca(OH)₂), so we need 2 CaS molecules.
- Balance sulfur (S) atoms:
- 2 CaS provides 2 S atoms, and Ca(HS)₂ also has 2 S atoms, so this is balanced.
- Balance hydrogen (H) atoms:
- Ca(HS)₂ provides 2 H atoms, and Ca(OH)₂ provides 2 H atoms, so we need 2 H₂O molecules.
- Balance oxygen (O) atoms:
- 2 H₂O provides 2 O atoms, and Ca(OH)₂ provides 2 O atoms, so this is balanced.
$$
\boxed{2 \text{ CaS} + 2 \text{ H}_2\text{O} \rightarrow 1 \text{ Ca(HS)}_2 + 1 \text{ Ca(OH)}_2}
$$
---
- Balance gold (Au) atoms:
- There are 2 Au atoms in Au₂S₃, so we need 2 Au atoms on the right.
- Balance sulfur (S) atoms:
- There are 3 S atoms in Au₂S₃, so we need 3 H₂S molecules.
- Balance hydrogen (H) atoms:
- 3 H₂S provides 6 H atoms, so we need 3 H₂ molecules.
$$
\boxed{1 \text{ Au}_2\text{S}_3 + 3 \text{ H}_2 \rightarrow 2 \text{ Au} + 3 \text{ H}_2\text{S}}
$$
---
- Balance phosphorus (P) atoms:
- There is 1 P atom in PCl₅ and 1 P atom in H₃PO₄, so PCl₅ is already balanced.
- Balance chlorine (Cl) atoms:
- PCl₅ provides 5 Cl atoms, so we need 5 HCl molecules.
- Balance hydrogen (H) atoms:
- H₃PO₄ provides 3 H atoms, and 5 HCl provides 5 H atoms, so we need 8 H atoms from H₂O. This means 4 H₂O molecules.
- Balance oxygen (O) atoms:
- 4 H₂O provides 4 O atoms, and H₃PO₄ provides 4 O atoms, so this is balanced.
$$
\boxed{1 \text{ PCl}_5 + 4 \text{ H}_2\text{O} \rightarrow 1 \text{ H}_3\text{PO}_4 + 5 \text{ HCl}}
$$
---
- Balance barium (Ba) atoms:
- There are 3 Ba atoms in Ba₃N₂, so we need 3 BaF₂ molecules.
- Balance nitrogen (N) atoms:
- Ba₃N₂ provides 2 N atoms, so we need 2 NH₃ molecules.
- Balance fluorine (F) atoms:
- 3 BaF₂ provides 6 F atoms, and 2 NH₃ provides 0 F atoms, so we need 6 HF molecules.
$$
\boxed{1 \text{ Ba}_3\text{N}_2 + 6 \text{ HF} \rightarrow 3 \text{ BaF}_2 + 2 \text{ NH}_3}
$$
---
- Balance calcium (Ca) atoms:
- There are 3 Ca atoms in Ca₃(PO₄)₂, so we need 3 CaCl₂ molecules.
- Balance phosphate (PO₄) groups:
- There are 2 PO₄ groups in Ca₃(PO₄)₂, so we need 2 Na₃PO₄ molecules.
- Balance sodium (Na) atoms:
- 2 Na₃PO₄ provides 6 Na atoms, so we need 6 NaCl molecules.
- Balance chlorine (Cl) atoms:
- 3 CaCl₂ provides 6 Cl atoms, and 6 NaCl provides 6 Cl atoms, so this is balanced.
$$
\boxed{3 \text{ CaCl}_2 + 2 \text{ Na}_3\text{PO}_4 \rightarrow 1 \text{ Ca}_3(\text{PO}_4)_2 + 6 \text{ NaCl}}
$$
---
- Balance iron (Fe) atoms:
- There are 2 Fe atoms in Fe₂O₃, so we need 2 FeS molecules.
- Balance sulfur (S) atoms:
- 2 FeS provides 2 S atoms, so we need 2 SO₂ molecules.
- Balance oxygen (O) atoms:
- Fe₂O₃ provides 3 O atoms, and 2 SO₂ provides 4 O atoms, totaling 7 O atoms. We need 7/2 O₂ molecules, so multiply everything by 2.
$$
\boxed{4 \text{ FeS} + 7 \text{ O}_2 \rightarrow 2 \text{ Fe}_2\text{O}_3 + 4 \text{ SO}_2}
$$
---
- Balance phosphorus (P) atoms:
- There are 4 P atoms in P₄O₁₀, so we need 4 H₃PO₄ molecules.
- Balance chlorine (Cl) atoms:
- HClO₄ provides 1 Cl atom, and Cl₂O₇ requires 2 Cl atoms, so we need 2 HClO₄ molecules.
- Balance hydrogen (H) atoms:
- 2 HClO₄ provides 2 H atoms, and 4 H₃PO₄ requires 12 H atoms, so we need 10 H atoms from HClO₄. This means 10 HClO₄ molecules.
- Balance oxygen (O) atoms:
- 10 HClO₄ provides 40 O atoms, P₄O₁₀ provides 10 O atoms, and 4 H₃PO₄ provides 16 O atoms. The remaining O atoms go to Cl₂O₇, which requires 7 O atoms per molecule. We need 4 Cl₂O₇ molecules.
$$
\boxed{10 \text{ HClO}_4 + 1 \text{ P}_4\text{O}_{10} \rightarrow 4 \text{ H}_3\text{PO}_4 + 4 \text{ Cl}_2\text{O}_7}
$$
---
$$
\boxed{
\begin{aligned}
1. & \quad 3 \text{ KOH} + 1 \text{ H}_3\text{PO}_4 \rightarrow 1 \text{ K}_3\text{PO}_4 + 3 \text{ H}_2\text{O} \\
2. & \quad 4 \text{ NH}_3 + 5 \text{ O}_2 \rightarrow 4 \text{ NO} + 6 \text{ H}_2\text{O} \\
3. & \quad 4 \text{ Al} + 3 \text{ O}_2 \rightarrow 2 \text{ Al}_2\text{O}_3 \\
4. & \quad 2 \text{ CaS} + 2 \text{ H}_2\text{O} \rightarrow 1 \text{ Ca(HS)}_2 + 1 \text{ Ca(OH)}_2 \\
5. & \quad 1 \text{ Au}_2\text{S}_3 + 3 \text{ H}_2 \rightarrow 2 \text{ Au} + 3 \text{ H}_2\text{S} \\
6. & \quad 1 \text{ PCl}_5 + 4 \text{ H}_2\text{O} \rightarrow 1 \text{ H}_3\text{PO}_4 + 5 \text{ HCl} \\
7. & \quad 1 \text{ Ba}_3\text{N}_2 + 6 \text{ HF} \rightarrow 3 \text{ BaF}_2 + 2 \text{ NH}_3 \\
8. & \quad 3 \text{ CaCl}_2 + 2 \text{ Na}_3\text{PO}_4 \rightarrow 1 \text{ Ca}_3(\text{PO}_4)_2 + 6 \text{ NaCl} \\
9. & \quad 4 \text{ FeS} + 7 \text{ O}_2 \rightarrow 2 \text{ Fe}_2\text{O}_3 + 4 \text{ SO}_2 \\
10. & \quad 10 \text{ HClO}_4 + 1 \text{ P}_4\text{O}_{10} \rightarrow 4 \text{ H}_3\text{PO}_4 + 4 \text{ Cl}_2\text{O}_7 \\
\end{aligned}
}
$$
---
1. KOH + H₃PO₄ → K₃PO₄ + H₂O
- Start by balancing the potassium (K) atoms:
- There are 3 K atoms in K₃PO₄, so we need 3 KOH molecules.
- Now balance the phosphorus (P) atoms:
- There is 1 P atom in H₃PO₄ and 1 P atom in K₃PO₄, so H₃PO₄ is already balanced.
- Balance the hydrogen (H) atoms:
- On the left, 3 KOH provides 3 H atoms, and H₃PO₄ provides 3 more H atoms, totaling 6 H atoms.
- On the right, H₂O needs 2 H atoms per molecule, so we need 3 H₂O molecules.
- Finally, check oxygen (O):
- On the left, H₃PO₄ has 4 O atoms.
- On the right, K₃PO₄ has 4 O atoms, and 3 H₂O provides 3 O atoms, totaling 7 O atoms. This is balanced.
Balanced Equation:
$$
\boxed{3 \text{ KOH} + 1 \text{ H}_3\text{PO}_4 \rightarrow 1 \text{ K}_3\text{PO}_4 + 3 \text{ H}_2\text{O}}
$$
---
2. NH₃ + O₂ → NO + H₂O
- Balance nitrogen (N) atoms:
- There is 1 N atom in NH₃ and 1 N atom in NO, so NH₃ is already balanced.
- Balance hydrogen (H) atoms:
- NH₃ provides 3 H atoms, so we need 3/2 H₂O molecules. To avoid fractions, multiply everything by 2.
- Balance oxygen (O) atoms:
- After multiplying by 2, we have 2 NH₃ → 2 NO + 3 H₂O. Now, there are 2 O atoms in 2 NO and 3 O atoms in 3 H₂O, totaling 5 O atoms. We need 5/2 O₂ molecules, so multiply by 2 again.
- Final balanced equation:
$$
\boxed{4 \text{ NH}_3 + 5 \text{ O}_2 \rightarrow 4 \text{ NO} + 6 \text{ H}_2\text{O}}
$$
---
3. Al + O₂ → Al₂O₃
- Balance aluminum (Al) atoms:
- There are 2 Al atoms in Al₂O₃, so we need 2 Al atoms on the left.
- Balance oxygen (O) atoms:
- There are 3 O atoms in Al₂O₃, so we need 3/2 O₂ molecules. Multiply everything by 2 to avoid fractions.
$$
\boxed{4 \text{ Al} + 3 \text{ O}_2 \rightarrow 2 \text{ Al}_2\text{O}_3}
$$
---
4. CaS + H₂O → Ca(HS)₂ + Ca(OH)₂
- Balance calcium (Ca) atoms:
- There are 2 Ca atoms on the right (1 in Ca(HS)₂ and 1 in Ca(OH)₂), so we need 2 CaS molecules.
- Balance sulfur (S) atoms:
- 2 CaS provides 2 S atoms, and Ca(HS)₂ also has 2 S atoms, so this is balanced.
- Balance hydrogen (H) atoms:
- Ca(HS)₂ provides 2 H atoms, and Ca(OH)₂ provides 2 H atoms, so we need 2 H₂O molecules.
- Balance oxygen (O) atoms:
- 2 H₂O provides 2 O atoms, and Ca(OH)₂ provides 2 O atoms, so this is balanced.
$$
\boxed{2 \text{ CaS} + 2 \text{ H}_2\text{O} \rightarrow 1 \text{ Ca(HS)}_2 + 1 \text{ Ca(OH)}_2}
$$
---
5. Au₂S₃ + H₂ → Au + H₂S
- Balance gold (Au) atoms:
- There are 2 Au atoms in Au₂S₃, so we need 2 Au atoms on the right.
- Balance sulfur (S) atoms:
- There are 3 S atoms in Au₂S₃, so we need 3 H₂S molecules.
- Balance hydrogen (H) atoms:
- 3 H₂S provides 6 H atoms, so we need 3 H₂ molecules.
$$
\boxed{1 \text{ Au}_2\text{S}_3 + 3 \text{ H}_2 \rightarrow 2 \text{ Au} + 3 \text{ H}_2\text{S}}
$$
---
6. PCl₅ + H₂O → H₃PO₄ + HCl
- Balance phosphorus (P) atoms:
- There is 1 P atom in PCl₅ and 1 P atom in H₃PO₄, so PCl₅ is already balanced.
- Balance chlorine (Cl) atoms:
- PCl₅ provides 5 Cl atoms, so we need 5 HCl molecules.
- Balance hydrogen (H) atoms:
- H₃PO₄ provides 3 H atoms, and 5 HCl provides 5 H atoms, so we need 8 H atoms from H₂O. This means 4 H₂O molecules.
- Balance oxygen (O) atoms:
- 4 H₂O provides 4 O atoms, and H₃PO₄ provides 4 O atoms, so this is balanced.
$$
\boxed{1 \text{ PCl}_5 + 4 \text{ H}_2\text{O} \rightarrow 1 \text{ H}_3\text{PO}_4 + 5 \text{ HCl}}
$$
---
7. Ba₃N₂ + HF → BaF₂ + NH₃
- Balance barium (Ba) atoms:
- There are 3 Ba atoms in Ba₃N₂, so we need 3 BaF₂ molecules.
- Balance nitrogen (N) atoms:
- Ba₃N₂ provides 2 N atoms, so we need 2 NH₃ molecules.
- Balance fluorine (F) atoms:
- 3 BaF₂ provides 6 F atoms, and 2 NH₃ provides 0 F atoms, so we need 6 HF molecules.
$$
\boxed{1 \text{ Ba}_3\text{N}_2 + 6 \text{ HF} \rightarrow 3 \text{ BaF}_2 + 2 \text{ NH}_3}
$$
---
8. CaCl₂ + Na₃PO₄ → Ca₃(PO₄)₂ + NaCl
- Balance calcium (Ca) atoms:
- There are 3 Ca atoms in Ca₃(PO₄)₂, so we need 3 CaCl₂ molecules.
- Balance phosphate (PO₄) groups:
- There are 2 PO₄ groups in Ca₃(PO₄)₂, so we need 2 Na₃PO₄ molecules.
- Balance sodium (Na) atoms:
- 2 Na₃PO₄ provides 6 Na atoms, so we need 6 NaCl molecules.
- Balance chlorine (Cl) atoms:
- 3 CaCl₂ provides 6 Cl atoms, and 6 NaCl provides 6 Cl atoms, so this is balanced.
$$
\boxed{3 \text{ CaCl}_2 + 2 \text{ Na}_3\text{PO}_4 \rightarrow 1 \text{ Ca}_3(\text{PO}_4)_2 + 6 \text{ NaCl}}
$$
---
9. FeS + O₂ → Fe₂O₃ + SO₂
- Balance iron (Fe) atoms:
- There are 2 Fe atoms in Fe₂O₃, so we need 2 FeS molecules.
- Balance sulfur (S) atoms:
- 2 FeS provides 2 S atoms, so we need 2 SO₂ molecules.
- Balance oxygen (O) atoms:
- Fe₂O₃ provides 3 O atoms, and 2 SO₂ provides 4 O atoms, totaling 7 O atoms. We need 7/2 O₂ molecules, so multiply everything by 2.
$$
\boxed{4 \text{ FeS} + 7 \text{ O}_2 \rightarrow 2 \text{ Fe}_2\text{O}_3 + 4 \text{ SO}_2}
$$
---
10. HClO₄ + P₄O₁₀ → H₃PO₄ + Cl₂O₇
- Balance phosphorus (P) atoms:
- There are 4 P atoms in P₄O₁₀, so we need 4 H₃PO₄ molecules.
- Balance chlorine (Cl) atoms:
- HClO₄ provides 1 Cl atom, and Cl₂O₇ requires 2 Cl atoms, so we need 2 HClO₄ molecules.
- Balance hydrogen (H) atoms:
- 2 HClO₄ provides 2 H atoms, and 4 H₃PO₄ requires 12 H atoms, so we need 10 H atoms from HClO₄. This means 10 HClO₄ molecules.
- Balance oxygen (O) atoms:
- 10 HClO₄ provides 40 O atoms, P₄O₁₀ provides 10 O atoms, and 4 H₃PO₄ provides 16 O atoms. The remaining O atoms go to Cl₂O₇, which requires 7 O atoms per molecule. We need 4 Cl₂O₇ molecules.
$$
\boxed{10 \text{ HClO}_4 + 1 \text{ P}_4\text{O}_{10} \rightarrow 4 \text{ H}_3\text{PO}_4 + 4 \text{ Cl}_2\text{O}_7}
$$
---
Final Answer:
$$
\boxed{
\begin{aligned}
1. & \quad 3 \text{ KOH} + 1 \text{ H}_3\text{PO}_4 \rightarrow 1 \text{ K}_3\text{PO}_4 + 3 \text{ H}_2\text{O} \\
2. & \quad 4 \text{ NH}_3 + 5 \text{ O}_2 \rightarrow 4 \text{ NO} + 6 \text{ H}_2\text{O} \\
3. & \quad 4 \text{ Al} + 3 \text{ O}_2 \rightarrow 2 \text{ Al}_2\text{O}_3 \\
4. & \quad 2 \text{ CaS} + 2 \text{ H}_2\text{O} \rightarrow 1 \text{ Ca(HS)}_2 + 1 \text{ Ca(OH)}_2 \\
5. & \quad 1 \text{ Au}_2\text{S}_3 + 3 \text{ H}_2 \rightarrow 2 \text{ Au} + 3 \text{ H}_2\text{S} \\
6. & \quad 1 \text{ PCl}_5 + 4 \text{ H}_2\text{O} \rightarrow 1 \text{ H}_3\text{PO}_4 + 5 \text{ HCl} \\
7. & \quad 1 \text{ Ba}_3\text{N}_2 + 6 \text{ HF} \rightarrow 3 \text{ BaF}_2 + 2 \text{ NH}_3 \\
8. & \quad 3 \text{ CaCl}_2 + 2 \text{ Na}_3\text{PO}_4 \rightarrow 1 \text{ Ca}_3(\text{PO}_4)_2 + 6 \text{ NaCl} \\
9. & \quad 4 \text{ FeS} + 7 \text{ O}_2 \rightarrow 2 \text{ Fe}_2\text{O}_3 + 4 \text{ SO}_2 \\
10. & \quad 10 \text{ HClO}_4 + 1 \text{ P}_4\text{O}_{10} \rightarrow 4 \text{ H}_3\text{PO}_4 + 4 \text{ Cl}_2\text{O}_7 \\
\end{aligned}
}
$$
Parent Tip: Review the logic above to help your child master the concept of balancing equation practice worksheet.
