Balancing Redox Equations WorkSheet - kurtniedenzu - Free Printable

To solve the given redox equations, we will follow the steps outlined in the worksheet. Let's go through each equation step by step.

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1. H₂S + HNO₃ → S + NO + H₂O

#### Step 1: Assign oxidation numbers
- H₂S: H = +1, S = -2
- HNO₃: H = +1, N = +5, O = -2
- S: S = 0
- NO: N = +2, O = -2
- H₂O: H = +1, O = -2

#### Step 2: Identify oxidation and reduction
- Oxidation: S in H₂S is oxidized from -2 to 0 (S).
- Reduction: N in HNO₃ is reduced from +5 to +2 (NO).

#### Step 3: Balance the atoms other than H and O
- S: 1 atom on both sides.
- N: 1 atom on both sides.
- O: 3 atoms in HNO₃, 2 atoms in NO, and 1 atom in H₂O (total 3 on the right side).

#### Step 4: Balance H and O using H₂O and H⁺
- Add 2 H₂O to the left side to balance O.
- Add 4 H⁺ to the left side to balance H.

#### Step 5: Check charge balance
- Left side: 4 H⁺ + HNO₃ (charge = +1)
- Right side: NO (charge = +2) + H₂O (neutral)

Add 1 e⁻ to the right side to balance the charge.

#### Final Equation:
\[ \boxed{\text{H}_2\text{S} + 2\text{H}^+ + 2\text{NO}_3^- \rightarrow \text{S} + 2\text{NO} + 2\text{H}_2\text{O}} \]

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2. H₂SO₄ + HBr → SO₂ + Br₂ + H₂O

#### Step 1: Assign oxidation numbers
- H₂SO₄: H = +1, S = +6, O = -2
- HBr: H = +1, Br = -1
- SO₂: S = +4, O = -2
- Br₂: Br = 0
- H₂O: H = +1, O = -2

#### Step 2: Identify oxidation and reduction
- Oxidation: Br in HBr is oxidized from -1 to 0 (Br₂).
- Reduction: S in H₂SO₄ is reduced from +6 to +4 (SO₂).

#### Step 3: Balance the atoms other than H and O
- S: 1 atom on both sides.
- Br: 2 atoms on the right side, so add 2 HBr on the left.
- O: 4 atoms in H₂SO₄, 2 atoms in SO₂, and 1 atom in H₂O (total 3 on the right side).

#### Step 4: Balance H and O using H₂O and H⁺
- Add 2 H₂O to the left side to balance O.
- Add 2 H⁺ to the left side to balance H.

#### Final Equation:
\[ \boxed{\text{H}_2\text{SO}_4 + 2\text{HBr} \rightarrow \text{SO}_2 + \text{Br}_2 + 2\text{H}_2\text{O}} \]

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3. H₂SO₄ + HI → H₂S + I₂ + H₂O

#### Step 1: Assign oxidation numbers
- H₂SO₄: H = +1, S = +6, O = -2
- HI: H = +1, I = -1
- H₂S: H = +1, S = -2
- I₂: I = 0
- H₂O: H = +1, O = -2

#### Step 2: Identify oxidation and reduction
- Oxidation: I in HI is oxidized from -1 to 0 (I₂).
- Reduction: S in H₂SO₄ is reduced from +6 to -2 (H₂S).

#### Step 3: Balance the atoms other than H and O
- S: 1 atom on both sides.
- I: 2 atoms on the right side, so add 2 HI on the left.
- O: 4 atoms in H₂SO₄, 1 atom in H₂O (total 4 on the right side).

#### Step 4: Balance H and O using H₂O and H⁺
- Add 2 H₂O to the left side to balance O.
- Add 2 H⁺ to the left side to balance H.

#### Final Equation:
\[ \boxed{\text{H}_2\text{SO}_4 + 8\text{HI} \rightarrow \text{H}_2\text{S} + 4\text{I}_2 + 4\text{H}_2\text{O}} \]

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4. N₂O + H₂ → H₂O + NH₃

#### Step 1: Assign oxidation numbers
- N₂O: N = +1, O = -2
- H₂: H = 0
- H₂O: H = +1, O = -2
- NH₃: N = -3, H = +1

#### Step 2: Identify oxidation and reduction
- Oxidation: H in H₂ is oxidized from 0 to +1 (H₂O).
- Reduction: N in N₂O is reduced from +1 to -3 (NH₃).

#### Step 3: Balance the atoms other than H and O
- N: 2 atoms on the left side, so add 2 NH₃ on the right.
- H: 2 atoms in H₂, 6 atoms in 2 NH₃, and 2 atoms in H₂O (total 8 on the right side).

#### Step 4: Balance O using H₂O
- Add 2 H₂O to the right side to balance O.

#### Final Equation:
\[ \boxed{\text{N}_2\text{O} + 3\text{H}_2 \rightarrow \text{H}_2\text{O} + 2\text{NH}_3} \]

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5. K + KNO₃ → N₂ + K₂O

#### Step 1: Assign oxidation numbers
- K: K = 0
- KNO₃: K = +1, N = +5, O = -2
- N₂: N = 0
- K₂O: K = +1, O = -2

#### Step 2: Identify oxidation and reduction
- Oxidation: K is oxidized from 0 to +1 (K₂O).
- Reduction: N in KNO₃ is reduced from +5 to 0 (N₂).

#### Step 3: Balance the atoms other than H and O
- K: 2 atoms on the right side, so add 2 K on the left.
- N: 2 atoms on the right side, so add 2 KNO₃ on the left.
- O: 6 atoms in 2 KNO₃, 1 atom in K₂O (total 7 on the right side).

#### Step 4: Balance O using K₂O
- Add 3 K₂O to the right side to balance O.

#### Final Equation:
\[ \boxed{4\text{K} + 2\text{KNO}_3 \rightarrow \text{N}_2 + 3\text{K}_2\text{O}} \]

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6. Fe₂O₃ + S → Fe + SO₂

#### Step 1: Assign oxidation numbers
- Fe₂O₃: Fe = +3, O = -2
- S: S = 0
- Fe: Fe = 0
- SO₂: S = +4, O = -2

#### Step 2: Identify oxidation and reduction
- Oxidation: S is oxidized from 0 to +4 (SO₂).
- Reduction: Fe in Fe₂O₃ is reduced from +3 to 0 (Fe).

#### Step 3: Balance the atoms other than H and O
- Fe: 2 atoms on the left side, so add 2 Fe on the right.
- S: 1 atom on both sides.
- O: 3 atoms in Fe₂O₃, 2 atoms in SO₂ (total 5 on the right side).

#### Step 4: Balance O using SO₂
- Add 3/2 SO₂ to the right side to balance O.

#### Final Equation:
\[ \boxed{\text{Fe}_2\text{O}_3 + 3\text{S} \rightarrow 2\text{Fe} + 3\text{SO}_2} \]

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7. NH₃ + O₂ → NO + H₂O

#### Step 1: Assign oxidation numbers
- NH₃: N = -3, H = +1
- O₂: O = 0
- NO: N = +2, O = -2
- H₂O: H = +1, O = -2

#### Step 2: Identify oxidation and reduction
- Oxidation: N in NH₃ is oxidized from -3 to +2 (NO).
- Reduction: O in O₂ is reduced from 0 to -2 (H₂O).

#### Step 3: Balance the atoms other than H and O
- N: 1 atom on both sides.
- O: 2 atoms in O₂, 1 atom in NO, and 1 atom in H₂O (total 2 on the right side).

#### Step 4: Balance H and O using H₂O
- Add 3 H₂O to the right side to balance O.
- Add 6 H⁺ to the left side to balance H.

#### Final Equation:
\[ \boxed{4\text{NH}_3 + 5\text{O}_2 \rightarrow 4\text{NO} + 6\text{H}_2\text{O}} \]

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Final Answers:

1. \( \boxed{\text{H}_2\text{S} + 2\text{H}^+ + 2\text{NO}_3^- \rightarrow \text{S} + 2\text{NO} + 2\text{H}_2\text{O}} \)
2. \( \boxed{\text{H}_2\text{SO}_4 + 2\text{HBr} \rightarrow \text{SO}_2 + \text{Br}_2 + 2\text{H}_2\text{O}} \)
3. \( \boxed{\text{H}_2\text{SO}_4 + 8\text{HI} \rightarrow \text{H}_2\text{S} + 4\text{I}_2 + 4\text{H}_2\text{O}} \)
4. \( \boxed{\text{N}_2\text{O} + 3\text{H}_2 \rightarrow \text{H}_2\text{O} + 2\text{NH}_3} \)
5. \( \boxed{4\text{K} + 2\text{KNO}_3 \rightarrow \text{N}_2 + 3\text{K}_2\text{O}} \)
6. \( \boxed{\text{Fe}_2\text{O}_3 + 3\text{S} \rightarrow 2\text{Fe} + 3\text{SO}_2} \)
7. \( \boxed{4\text{NH}_3 + 5\text{O}_2 \rightarrow 4\text{NO} + 6\text{H}_2\text{O}} \)