Chemistry stoichiometry problems | PDF - Free Printable

Problem Analysis:

The worksheet involves solving stoichiometry problems using balanced chemical equations. The key steps for each problem are:
1. Balance the chemical equation.
2. Use the balanced equation to determine mole ratios.
3. Apply the given information to calculate the required quantities.

Let's solve each problem step by step.

---

Problem 1: NO + O₂ → NO₂

#### a. 2 moles of NO will react with _______ mole(s) of O₂ to produce _______ mole(s) of NO₂.

1. Balance the equation:
\[
2\text{NO} + \text{O}_2 \rightarrow 2\text{NO}_2
\]

2. Analyze the mole ratio:
- From the balanced equation, 2 moles of NO react with 1 mole of O₂ to produce 2 moles of NO₂.
- Therefore, if 2 moles of NO are used:
- Moles of O₂ required = \( \frac{1}{2} \times 2 = 1 \) mole.
- Moles of NO₂ produced = \( \frac{2}{2} \times 2 = 2 \) moles.

Answer:
\[
\boxed{1, 2}
\]

#### b. How many moles of NO must react to form 4.67 moles of NO₂?

1. From the balanced equation:
- 2 moles of NO produce 2 moles of NO₂.
- Therefore, the mole ratio of NO to NO₂ is 1:1.

2. Calculate moles of NO needed:
- If 4.67 moles of NO₂ are produced, then:
\[
\text{Moles of NO} = 4.67 \text{ moles of NO₂}
\]

Answer:
\[
\boxed{4.67}
\]

---

Problem 2: Ni + H₂SO₄ → NiSO₄ + H₂

#### a. 20 moles of Ni will produce _______ moles of H₂O.

1. Balance the equation:
\[
\text{Ni} + \text{H}_2\text{SO}_4 \rightarrow \text{NiSO}_4 + \text{H}_2
\]
(Note: There is no H₂O in the products. The question might have a typo. Assuming it asks about H₂ instead.)

2. Analyze the mole ratio:
- From the balanced equation, 1 mole of Ni produces 1 mole of H₂.
- Therefore, if 20 moles of Ni are used:
\[
\text{Moles of H}_2 = 20 \text{ moles of Ni}
\]

Answer:
\[
\boxed{20}
\]

#### b. How many moles of Ni will be produced if 3.5 moles of H₂ react?

1. From the balanced equation:
- 1 mole of H₂ is produced from 1 mole of Ni.
- Therefore, if 3.5 moles of H₂ are produced:
\[
\text{Moles of Ni} = 3.5 \text{ moles of H}_2
\]

Answer:
\[
\boxed{3.5}
\]

---

Problem 3: Al + Fe₂O₃ → Al₂O₃ + Fe

#### a. 20 moles of Al will produce _______ moles of Fe.

1. Balance the equation:
\[
2\text{Al} + \text{Fe}_2\text{O}_3 \rightarrow \text{Al}_2\text{O}_3 + 2\text{Fe}
\]

2. Analyze the mole ratio:
- From the balanced equation, 2 moles of Al produce 2 moles of Fe.
- Therefore, if 20 moles of Al are used:
\[
\text{Moles of Fe} = \frac{2}{2} \times 20 = 20 \text{ moles}
\]

Answer:
\[
\boxed{20}
\]

#### b. How many moles of AlF₃ will be produced with 0.6 moles of Fe?

1. Relevant reaction (not provided in the problem):
- Assume the reaction is:
\[
\text{Fe} + 3\text{AlF}_3 \rightarrow \text{Al}_2\text{O}_3 + 3\text{FeF}_2
\]
- However, the problem does not specify this reaction. Let’s assume the question is about the initial reaction involving Al and Fe₂O₃.

2. From the balanced equation:
- 2 moles of Al produce 2 moles of Fe.
- Therefore, if 0.6 moles of Fe are produced, the moles of Al required are:
\[
\text{Moles of Al} = \frac{2}{2} \times 0.6 = 0.6 \text{ moles}
\]
- Since the question asks for AlF₃, we need the reaction involving Al and F:
\[
2\text{Al} + 3\text{F}_2 \rightarrow 2\text{AlF}_3
\]
- From this, 2 moles of Al produce 2 moles of AlF₃.
- Therefore, if 0.6 moles of Al are used:
\[
\text{Moles of AlF}_3 = \frac{2}{2} \times 0.6 = 0.6 \text{ moles}
\]

Answer:
\[
\boxed{0.6}
\]

---

Problem 4: C₂H₆ + O₂ → CO₂ + H₂O

#### a. How many moles of oxygen react with 11 moles of C₂H₆?

1. Balance the equation:
\[
2\text{C}_2\text{H}_6 + 7\text{O}_2 \rightarrow 4\text{CO}_2 + 6\text{H}_2\text{O}
\]

2. Analyze the mole ratio:
- From the balanced equation, 2 moles of C₂H₆ react with 7 moles of O₂.
- Therefore, if 11 moles of C₂H₆ are used:
\[
\text{Moles of O}_2 = \frac{7}{2} \times 11 = 38.5 \text{ moles}
\]

Answer:
\[
\boxed{38.5}
\]

#### b. How many moles of CO₂ are produced if 3.5 moles of water are produced?

1. From the balanced equation:
- 6 moles of H₂O are produced from 4 moles of CO₂.
- Therefore, the mole ratio of CO₂ to H₂O is \( \frac{4}{6} = \frac{2}{3} \).

2. Calculate moles of CO₂:
- If 3.5 moles of H₂O are produced:
\[
\text{Moles of CO}_2 = \frac{2}{3} \times 3.5 = \frac{7}{3} \approx 2.33 \text{ moles}
\]

Answer:
\[
\boxed{2.33}
\]

---

Problem 5: O₂ + Fe → FeO₃

#### a. Fill in the following word equation: _______ moles of oxygen gas react with _______ moles of iron to produce _______ moles of iron (III) oxide.

1. Balance the equation:
\[
3\text{O}_2 + 4\text{Fe} \rightarrow 2\text{Fe}_2\text{O}_3
\]

2. Analyze the mole ratio:
- From the balanced equation:
- 3 moles of O₂ react with 4 moles of Fe to produce 2 moles of Fe₂O₃.

Answer:
\[
\boxed{3, 4, 2}
\]

#### b. How many moles of O₂ are required to produce 3.0 moles of Fe₂O₃?

1. From the balanced equation:
- 3 moles of O₂ produce 2 moles of Fe₂O₃.
- Therefore, if 3.0 moles of Fe₂O₃ are produced:
\[
\text{Moles of O}_2 = \frac{3}{2} \times 3.0 = 4.5 \text{ moles}
\]

Answer:
\[
\boxed{4.5}
\]

---

Final Answers:

1. a. \( \boxed{1, 2} \)
b. \( \boxed{4.67} \)
2. a. \( \boxed{20} \)
b. \( \boxed{3.5} \)
3. a. \( \boxed{20} \)
b. \( \boxed{0.6} \)
4. a. \( \boxed{38.5} \)
b. \( \boxed{2.33} \)
5. a. \( \boxed{3, 4, 2} \)
b. \( \boxed{4.5} \)

Final Boxed Answer:
\[
\boxed{1, 2, 4.67, 20, 3.5, 20, 0.6, 38.5, 2.33, 3, 4, 2, 4.5}
\]