Stoichiometry practice problems involving mole-to-mole conversions for various chemical reactions.

Let's solve each problem step-by-step using stoichiometry, which involves using the balanced chemical equations to find mole ratios between reactants and products.

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Reaction 1:

2 KClO₃ → 2 KCl + 3 O₂

#### 1. How many moles of O₂ will be formed from 1.65 moles of KClO₃?

From the equation:
- 2 mol KClO₃ → 3 mol O₂
- So, mole ratio: $\frac{3 \text{ mol O}_2}{2 \text{ mol KClO}_3}$

$$
1.65 \text{ mol KClO}_3 \times \frac{3 \text{ mol O}_2}{2 \text{ mol KClO}_3} = \frac{1.65 \times 3}{2} = 2.475 \text{ mol O}_2
$$

✔ Answer: 2.475 mol O₂

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#### 2. How many moles of KClO₃ are needed to make 3.50 moles of KCl?

From the equation:
- 2 mol KClO₃ → 2 mol KCl
- So, mole ratio: $\frac{2 \text{ mol KClO}_3}{2 \text{ mol KCl}} = 1:1$

$$
3.50 \text{ mol KCl} \times \frac{2 \text{ mol KClO}_3}{2 \text{ mol KCl}} = 3.50 \text{ mol KClO}_3
$$

✔ Answer: 3.50 mol KClO₃

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#### 3. How many moles of KCl will be formed from 2.73 moles of KClO₃?

From the equation:
- 2 mol KClO₃ → 2 mol KCl → 1:1 ratio

$$
2.73 \text{ mol KClO}_3 \times \frac{2 \text{ mol KCl}}{2 \text{ mol KClO}_3} = 2.73 \text{ mol KCl}
$$

✔ Answer: 2.73 mol KCl

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Reaction 2:

4 Fe + 3 O₂ → 2 Fe₂O₃

#### 4. How many moles of Fe₂O₃ are produced when 0.275 moles of Fe is reacted?

From the equation:
- 4 mol Fe → 2 mol Fe₂O₃
- Mole ratio: $\frac{2 \text{ mol Fe}_2\text{O}_3}{4 \text{ mol Fe}} = \frac{1}{2}$

$$
0.275 \text{ mol Fe} \times \frac{2 \text{ mol Fe}_2\text{O}_3}{4 \text{ mol Fe}} = 0.275 \times 0.5 = 0.1375 \text{ mol Fe}_2\text{O}_3
$$

✔ Answer: 0.1375 mol Fe₂O₃

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#### 5. How many moles of Fe₂O₃ are produced when 31.0 moles of O₂ is reacted?

From the equation:
- 3 mol O₂ → 2 mol Fe₂O₃
- Ratio: $\frac{2 \text{ mol Fe}_2\text{O}_3}{3 \text{ mol O}_2}$

$$
31.0 \text{ mol O}_2 \times \frac{2 \text{ mol Fe}_2\text{O}_3}{3 \text{ mol O}_2} = \frac{62.0}{3} = 20.67 \text{ mol Fe}_2\text{O}_3
$$

✔ Answer: 20.7 mol Fe₂O₃ (rounded to one decimal place)

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#### 6. How many moles of O₂ are needed to react with 8.9 moles of Fe?

From the equation:
- 4 mol Fe → 3 mol O₂
- Ratio: $\frac{3 \text{ mol O}_2}{4 \text{ mol Fe}}$

$$
8.9 \text{ mol Fe} \times \frac{3 \text{ mol O}_2}{4 \text{ mol Fe}} = \frac{26.7}{4} = 6.675 \text{ mol O}_2
$$

✔ Answer: 6.68 mol O₂ (rounded to two decimals)

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Reaction 3:

2 H₂O → 2 H₂ + O₂

#### 7. How many moles of O₂ are produced when 1.26 moles of H₂O is reacted?

From the equation:
- 2 mol H₂O → 1 mol O₂
- Ratio: $\frac{1 \text{ mol O}_2}{2 \text{ mol H}_2\text{O}}$

$$
1.26 \text{ mol H}_2\text{O} \times \frac{1 \text{ mol O}_2}{2 \text{ mol H}_2\text{O}} = 0.63 \text{ mol O}_2
$$

✔ Answer: 0.63 mol O₂

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#### 8. How many moles of H₂O are needed to produce 55.7 moles of H₂?

From the equation:
- 2 mol H₂O → 2 mol H₂ → 1:1 ratio

$$
55.7 \text{ mol H}_2 \times \frac{2 \text{ mol H}_2\text{O}}{2 \text{ mol H}_2} = 55.7 \text{ mol H}_2\text{O}
$$

✔ Answer: 55.7 mol H₂O

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#### 9. If enough H₂O is reacted to produce 3.40 moles of H₂, then how many moles of O₂ must have been made?

From the equation:
- 2 H₂O → 2 H₂ + 1 O₂
- So, for every 2 moles of H₂ produced, 1 mole of O₂ is produced.

So the ratio is:
- 2 mol H₂ → 1 mol O₂

$$
3.40 \text{ mol H}_2 \times \frac{1 \text{ mol O}_2}{2 \text{ mol H}_2} = 1.70 \text{ mol O}_2
$$

✔ Answer: 1.70 mol O₂

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✔ Final Answers Summary:

1. 2.475 mol O₂
2. 3.50 mol KClO₃
3. 2.73 mol KCl
4. 0.1375 mol Fe₂O₃
5. 20.7 mol Fe₂O₃
6. 6.68 mol O₂
7. 0.63 mol O₂
8. 55.7 mol H₂O
9. 1.70 mol O₂

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