49 Balancing Chemical Equations Worksheets [with Answers] - Free Printable

Problem: Balancing Chemical Equations

The task is to balance the given chemical equations. Below, I will solve each equation step by step.

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#### 1. Phosphorus (P₄) + Oxygen → Diphosphorus Pentoxide
Unbalanced Equation:
\[ \text{P}_4 + \text{O}_2 \rightarrow \text{P}_2\text{O}_5 \]

Step-by-Step Solution:
1. Start with the unbalanced equation.
2. Balance phosphorus (P): There are 4 P atoms on the left and 2 P atoms on the right. To balance P, multiply \(\text{P}_2\text{O}_5\) by 2:
\[ \text{P}_4 + \text{O}_2 \rightarrow 2\text{P}_2\text{O}_5 \]
3. Now, balance oxygen (O): There are 2 O atoms on the left and \(2 \times 5 = 10\) O atoms on the right. To balance O, multiply \(\text{O}_2\) by 5:
\[ \text{P}_4 + 5\text{O}_2 \rightarrow 2\text{P}_2\text{O}_5 \]

Balanced Equation:
\[ \boxed{\text{P}_4 + 5\text{O}_2 \rightarrow 2\text{P}_2\text{O}_5} \]

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#### 2. Potassium Hydroxide → Potassium Oxide + Water
Unbalanced Equation:
\[ 2\text{KOH} \rightarrow \text{K}_2\text{O} + \text{H}_2\text{O} \]

Step-by-Step Solution:
1. Start with the unbalanced equation.
2. Balance potassium (K): There are 2 K atoms on the left and 2 K atoms on the right. K is already balanced.
3. Balance oxygen (O): There are 2 O atoms on the left and \(1 + 1 = 2\) O atoms on the right. O is already balanced.
4. Balance hydrogen (H): There are 2 H atoms on the left and 2 H atoms on the right. H is already balanced.

Balanced Equation:
\[ \boxed{2\text{KOH} \rightarrow \text{K}_2\text{O} + \text{H}_2\text{O}} \]

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#### 3. Aluminum + Copper(II) Nitrate → Aluminum Nitrate + Copper
Unbalanced Equation:
\[ \text{Al} + \text{Cu(NO}_3)_2 \rightarrow \text{Al(NO}_3)_3 + \text{Cu} \]

Step-by-Step Solution:
1. Start with the unbalanced equation.
2. Balance aluminum (Al): There is 1 Al atom on the left and 1 Al atom on the right. To balance Al, multiply \(\text{Al}\) by 2 and \(\text{Al(NO}_3)_3\) by 2:
\[ 2\text{Al} + \text{Cu(NO}_3)_2 \rightarrow 2\text{Al(NO}_3)_3 + \text{Cu} \]
3. Balance copper (Cu): There is 1 Cu atom on the left and 1 Cu atom on the right. Cu is already balanced.
4. Balance nitrate (\(\text{NO}_3\)): There are 2 \(\text{NO}_3\) groups on the left and \(2 \times 3 = 6\) \(\text{NO}_3\) groups on the right. To balance \(\text{NO}_3\), multiply \(\text{Cu(NO}_3)_2\) by 3:
\[ 2\text{Al} + 3\text{Cu(NO}_3)_2 \rightarrow 2\text{Al(NO}_3)_3 + 3\text{Cu} \]

Balanced Equation:
\[ \boxed{2\text{Al} + 3\text{Cu(NO}_3)_2 \rightarrow 2\text{Al(NO}_3)_3 + 3\text{Cu}} \]

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#### 4. Pentane (C₅H₁₂) + Oxygen → Carbon Dioxide + Water
Unbalanced Equation:
\[ \text{C}_5\text{H}_{12} + \text{O}_2 \rightarrow \text{CO}_2 + \text{H}_2\text{O} \]

Step-by-Step Solution:
1. Start with the unbalanced equation.
2. Balance carbon (C): There are 5 C atoms on the left and 1 C atom on the right. To balance C, multiply \(\text{CO}_2\) by 5:
\[ \text{C}_5\text{H}_{12} + \text{O}_2 \rightarrow 5\text{CO}_2 + \text{H}_2\text{O} \]
3. Balance hydrogen (H): There are 12 H atoms on the left and 2 H atoms on the right. To balance H, multiply \(\text{H}_2\text{O}\) by 6:
\[ \text{C}_5\text{H}_{12} + \text{O}_2 \rightarrow 5\text{CO}_2 + 6\text{H}_2\text{O} \]
4. Balance oxygen (O): There are 2 O atoms on the left and \(5 \times 2 + 6 = 16\) O atoms on the right. To balance O, multiply \(\text{O}_2\) by 8:
\[ \text{C}_5\text{H}_{12} + 8\text{O}_2 \rightarrow 5\text{CO}_2 + 6\text{H}_2\text{O} \]

Balanced Equation:
\[ \boxed{\text{C}_5\text{H}_{12} + 8\text{O}_2 \rightarrow 5\text{CO}_2 + 6\text{H}_2\text{O}} \]

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#### 5. Ammonium Dichromate → Chromium(III) Oxide + Nitrogen + Water
Unbalanced Equation:
\[ (\text{NH}_4)_2\text{Cr}_2\text{O}_7 \rightarrow \text{Cr}_2\text{O}_3 + \text{N}_2 + \text{H}_2\text{O} \]

Step-by-Step Solution:
1. Start with the unbalanced equation.
2. Balance chromium (Cr): There are 2 Cr atoms on the left and 2 Cr atoms on the right. Cr is already balanced.
3. Balance nitrogen (N): There are 2 N atoms on the left and 2 N atoms on the right. N is already balanced.
4. Balance hydrogen (H): There are \(2 \times 4 = 8\) H atoms on the left and 2 H atoms on the right. To balance H, multiply \(\text{H}_2\text{O}\) by 4:
\[ (\text{NH}_4)_2\text{Cr}_2\text{O}_7 \rightarrow \text{Cr}_2\text{O}_3 + \text{N}_2 + 4\text{H}_2\text{O} \]
5. Balance oxygen (O): There are \(7 + 2 \times 4 = 15\) O atoms on the left and \(3 + 4 = 7\) O atoms on the right. To balance O, multiply \(\text{Cr}_2\text{O}_3\) by 2:
\[ (\text{NH}_4)_2\text{Cr}_2\text{O}_7 \rightarrow 2\text{Cr}_2\text{O}_3 + \text{N}_2 + 4\text{H}_2\text{O} \]

Balanced Equation:
\[ \boxed{(\text{NH}_4)_2\text{Cr}_2\text{O}_7 \rightarrow 2\text{Cr}_2\text{O}_3 + \text{N}_2 + 4\text{H}_2\text{O}} \]

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#### 6. Barium Chloride + Sodium Hydroxide → Sodium Chloride + Barium Hydroxide
Unbalanced Equation:
\[ \text{BaCl}_2 + \text{NaOH} \rightarrow \text{NaCl} + \text{Ba(OH)}_2 \]

Step-by-Step Solution:
1. Start with the unbalanced equation.
2. Balance barium (Ba): There is 1 Ba atom on the left and 1 Ba atom on the right. Ba is already balanced.
3. Balance chlorine (Cl): There are 2 Cl atoms on the left and 1 Cl atom on the right. To balance Cl, multiply \(\text{NaCl}\) by 2:
\[ \text{BaCl}_2 + \text{NaOH} \rightarrow 2\text{NaCl} + \text{Ba(OH)}_2 \]
4. Balance sodium (Na): There is 1 Na atom on the left and 2 Na atoms on the right. To balance Na, multiply \(\text{NaOH}\) by 2:
\[ \text{BaCl}_2 + 2\text{NaOH} \rightarrow 2\text{NaCl} + \text{Ba(OH)}_2 \]
5. Balance hydroxide (\(\text{OH}\)): There are 2 \(\text{OH}\) groups on the left and 2 \(\text{OH}\) groups on the right. \(\text{OH}\) is already balanced.

Balanced Equation:
\[ \boxed{\text{BaCl}_2 + 2\text{NaOH} \rightarrow 2\text{NaCl} + \text{Ba(OH)}_2} \]

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#### 7. Nickel Chlorate → Nickel Chloride + Oxygen
Unbalanced Equation:
\[ \text{Ni(ClO}_3)_2 \rightarrow \text{NiCl}_2 + \text{O}_2 \]

Step-by-Step Solution:
1. Start with the unbalanced equation.
2. Balance nickel (Ni): There is 1 Ni atom on the left and 1 Ni atom on the right. Ni is already balanced.
3. Balance chlorine (Cl): There are 2 Cl atoms on the left and 2 Cl atoms on the right. Cl is already balanced.
4. Balance oxygen (O): There are \(2 \times 3 = 6\) O atoms on the left and 2 O atoms on the right. To balance O, multiply \(\text{O}_2\) by 3:
\[ \text{Ni(ClO}_3)_2 \rightarrow \text{NiCl}_2 + 3\text{O}_2 \]

Balanced Equation:
\[ \boxed{\text{Ni(ClO}_3)_2 \rightarrow \text{NiCl}_2 + 3\text{O}_2} \]

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#### 8. Aluminum + Hydrochloric Acid → Aluminum Chloride + Hydrogen
Unbalanced Equation:
\[ \text{Al} + \text{HCl} \rightarrow \text{AlCl}_3 + \text{H}_2 \]

Step-by-Step Solution:
1. Start with the unbalanced equation.
2. Balance aluminum (Al): There is 1 Al atom on the left and 1 Al atom on the right. Al is already balanced.
3. Balance chlorine (Cl): There is 1 Cl atom on the left and 3 Cl atoms on the right. To balance Cl, multiply \(\text{HCl}\) by 3:
\[ \text{Al} + 3\text{HCl} \rightarrow \text{AlCl}_3 + \text{H}_2 \]
4. Balance hydrogen (H): There are 3 H atoms on the left and 2 H atoms on the right. To balance H, multiply \(\text{H}_2\) by \(\frac{3}{2}\). Since we cannot have fractional coefficients, multiply the entire equation by 2:
\[ 2\text{Al} + 6\text{HCl} \rightarrow 2\text{AlCl}_3 + 3\text{H}_2 \]

Balanced Equation:
\[ \boxed{2\text{Al} + 6\text{HCl} \rightarrow 2\text{AlCl}_3 + 3\text{H}_2} \]

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Final Answer:

\[ \boxed{
\begin{aligned}
1. & \quad \text{P}_4 + 5\text{O}_2 \rightarrow 2\text{P}_2\text{O}_5 \\
2. & \quad 2\text{KOH} \rightarrow \text{K}_2\text{O} + \text{H}_2\text{O} \\
3. & \quad 2\text{Al} + 3\text{Cu(NO}_3)_2 \rightarrow 2\text{Al(NO}_3)_3 + 3\text{Cu} \\
4. & \quad \text{C}_5\text{H}_{12} + 8\text{O}_2 \rightarrow 5\text{CO}_2 + 6\text{H}_2\text{O} \\
5. & \quad (\text{NH}_4)_2\text{Cr}_2\text{O}_7 \rightarrow 2\text{Cr}_2\text{O}_3 + \text{N}_2 + 4\text{H}_2\text{O} \\
6. & \quad \text{BaCl}_2 + 2\text{NaOH} \rightarrow 2\text{NaCl} + \text{Ba(OH)}_2 \\
7. & \quad \text{Ni(ClO}_3)_2 \rightarrow \text{NiCl}_2 + 3\text{O}_2 \\
8. & \quad 2\text{Al} + 6\text{HCl} \rightarrow 2\text{AlCl}_3 + 3\text{H}_2 \\
\end{aligned}
} \]