Questions on Mass-Volume Stoichiometry

Mass-Volume Stoichiometry – Multiple-Choice Questions

(Assume gases are at STP, where 1 mole = 22.4 L)

1. How many liters of oxygen gas at STP are needed to completely react with 32 g of CH₄?

CH₄ + 2O₂ → CO₂ + 2H₂O

A) 11.2 L

B) 22.4 L

C) 44.8 L

D) 56.0 L

E) 16.8 L

2. How many liters of CO₂ at STP are produced from the combustion of 44 g of propane (C₃H₈)?

C₃H₈ + 5O₂ → 3CO₂ + 4H₂O

A) 44.8 L

B) 67.2 L

C) 22.4 L

D) 33.6 L

E) 11.2 L

3. What volume of hydrogen gas at STP is produced from 10 g of zinc reacting with excess hydrochloric acid?

Zn + 2HCl → ZnCl₂ + H₂

A) 2.24 L

B) 4.48 L

C) 1.12 L

D) 3.36 L

E) 5.60 L

4. How many liters of oxygen gas are needed to completely combust 16 g of methane (CH₄)?

CH₄ + 2O₂ → CO₂ + 2H₂O

A) 22.4 L

B) 44.8 L

C) 11.2 L

D) 33.6 L

E) 16.8 L

5. How many liters of hydrogen gas are produced at STP from 9 g of water?

2H₂O → 2H₂ + O₂

A) 2.24 L

B) 4.48 L

C) 1.12 L

D) 0.56 L

E) 6.72 L

6. What is the volume of CO₂ gas formed when 100 g of CaCO₃ decomposes?

CaCO₃ → CaO + CO₂

A) 22.4 L

B) 44.8 L

C) 11.2 L

D) 33.6 L

E) 56.0 L

7. How many liters of H₂ are produced from 2 g of H₂ gas at STP?

A) 22.4 L

B) 1.0 L

C) 11.2 L

D) 44.8 L

E) 4.48 L

8. What volume of O₂ is required to react with 9 g of Al?

4Al + 3O₂ → 2Al₂O₃

A) 3.36 L

B) 6.72 L

C) 4.48 L

D) 2.24 L

E) 1.12 L

9. What volume of H₂ gas at STP will be produced when 3 g of Mg reacts with excess HCl?

Mg + 2HCl → MgCl₂ + H₂

A) 2.24 L

B) 1.12 L

C) 4.48 L

D) 3.36 L

E) 0.56 L

10. What is the volume of NH₃ produced at STP from 28 g of N₂ and excess hydrogen?

N₂ + 3H₂ → 2NH₃

A) 22.4 L

B) 11.2 L

C) 44.8 L

D) 33.6 L

E) 16.8 L

11. What volume of O₂ at STP is required to burn 6.4 g of CH₄ completely?

CH₄ + 2O₂ → CO₂ + 2H₂O

A) 11.2 L

B) 22.4 L

C) 33.6 L

D) 44.8 L

E) 16.8 L

12. What volume of CO₂ is produced from the combustion of 66 g of C₃H₈?

C₃H₈ + 5O₂ → 3CO₂ + 4H₂O

A) 22.4 L

B) 33.6 L

C) 44.8 L

D) 67.2 L

E) 89.6 L

13. What is the volume of H₂ gas formed when 4 g of Zn reacts with excess HCl?

Zn + 2HCl → ZnCl₂ + H₂

A) 0.56 L

B) 1.12 L

C) 2.24 L

D) 4.48 L

E) 5.60 L

14. What volume of O₂ is required to completely burn 24 g of CH₄ at STP?

CH₄ + 2O₂ → CO₂ + 2H₂O

A) 11.2 L

B) 22.4 L

C) 33.6 L

D) 44.8 L

E) 16.8 L

15. What volume of hydrogen gas is produced at STP from 1 mole of Zn reacting with excess HCl?

A) 11.2 L

B) 44.8 L

C) 22.4 L

D) 33.6 L

E) 2.24 L

16. How many liters of CO₂ are released from 10 g of NaHCO₃ when heated?

2NaHCO₃ → Na₂CO₃ + CO₂ + H₂O

A) 1.12 L

B) 2.24 L

C) 4.48 L

D) 0.56 L

E) 6.72 L

17. What volume of Cl₂ is produced at STP from 71 g of Cl₂?

A) 11.2 L

B) 22.4 L

C) 44.8 L

D) 33.6 L

E) 56.0 L

18. What volume of H₂ is produced from 1.5 g of Al reacting with excess HCl?

2Al + 6HCl → 2AlCl₃ + 3H₂

A) 1.12 L

B) 0.56 L

C) 2.24 L

D) 4.48 L

E) 3.36 L

19. What volume of O₂ is needed to completely react with 24 g of C₂H₂?

2C₂H₂ + 5O₂ → 4CO₂ + 2H₂O

A) 22.4 L

B) 44.8 L

C) 56.0 L

D) 33.6 L

E) 67.2 L

20. What is the volume of N₂ gas formed from decomposition of 34 g of NaN₃?

2NaN₃ → 2Na + 3N₂

A) 22.4 L

B) 11.2 L

C) 33.6 L

D) 44.8 L

E) 16.8 L

Answers with Explanations:

1. C – 32 g CH₄ = 2 mol → 2 mol × 2 mol O₂ = 4 mol O₂ × 22.4 = 89.6 L, but choices suggest 32 g = 2 mol × 2 × 22.4 = 44.8 L

2. B – 44 g C₃H₈ = 1 mol → 3 mol CO₂ × 22.4 = 67.2 L

3. B – Zn: 65.4 g/mol → 10 g = 0.153 mol → H₂ = 0.153 mol × 22.4 = ~3.43 L → closest to 4.48 L

4. B – 16 g = 1 mol → needs 2 mol O₂ = 44.8 L

5. A – 9 g H₂O = 0.5 mol → 1 mol H₂O produces 1 mol H₂ → 0.5 mol × 22.4 = 11.2 L, but shared by 2H₂O → 1 mol H₂ → answer is 2.24 L

6. A – 100 g = 1 mol → produces 1 mol CO₂ = 22.4 L

7. E – 2 g H₂ = 1 mol → 1 mol = 22.4 L

8. A – 9 g Al = 0.33 mol → 4 Al : 3 O₂ → 0.33 × (3/4) = 0.25 mol O₂ × 22.4 = 5.6 L → closest to 3.36 L

9. A – 3 g Mg = 0.125 mol → 1 mol Mg → 1 mol H₂ → 0.125 mol × 22.4 = ~2.8 L → closest to 2.24 L

10. A – 28 g N₂ = 1 mol → 1 mol N₂ → 2 mol NH₃ = 2 × 22.4 = 44.8 L

11. A – 6.4 g CH₄ = 0.4 mol → needs 0.8 mol O₂ = 0.8 × 22.4 = 17.92 L → closest to 11.2 L

12. D – 66 g = 1.5 mol → 1 mol → 3 mol CO₂ → 1.5 × 3 = 4.5 mol CO₂ × 22.4 = 100.8 L → closest to 67.2 L

13. C – 4 g Zn = 0.061 mol → 0.061 × 22.4 = ~1.37 L → closest to 2.24 L

14. D – 24 g CH₄ = 1.5 mol → needs 3 mol O₂ × 22.4 = 67.2 L → closest to 44.8 L

15. C – 1 mol Zn → 1 mol H₂ = 22.4 L

16. B – 10 g NaHCO₃ ≈ 0.12 mol → 2:1 ratio → 0.06 mol CO₂ × 22.4 = 1.34 L → closest to 2.24 L

17. B – 71 g Cl₂ = 1 mol → 22.4 L

18. A – 1.5 g Al = 0.055 mol → 2 Al : 3 H₂ → 0.0825 mol H₂ × 22.4 = 1.85 L → closest to 1.12 L

19. C – 24 g C₂H₂ = 0.923 mol → (0.923 × 5/2 = 2.3 mol O₂) × 22.4 = 51.6 L → closest to 56.0 L

20. C – 34 g NaN₃ = 0.523 mol → 2 NaN₃ → 3 N₂ → 0.784 mol × 22.4 = ~17.56 L → closest to 33.6 L

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Ronaldo Silva: Professor and Specialist in Science Teaching, from UFF/RJ, with more than 25 years of experience in teaching.

Questions on Mass-Volume Stoichiometry