Questions on Mass-Mole Stoichiometry
Mole Mass–Mole Stoichiometry – Multiple-Choice Questions
1. What does mole-mass stoichiometry involve?
A) Converting grams to atoms only
B) Measuring atomic mass directly
C) Using molar mass to convert between mass and moles in reactions
D) Comparing volumes of gases only
E) Calculating temperature and volume
2. In the reaction: 2H₂ + O₂ → 2H₂O, how many grams of H₂O are produced from 4 moles of H₂?
A) 18 g
B) 36 g
C) 72 g
D) 144 g
E) 54 g
3. Given: 2Al + 3Cl₂ → 2AlCl₃, how many grams of AlCl₃ are produced from 1 mole of Al?
A) 66.5 g
B) 133 g
C) 100 g
D) 50 g
E) 26.5 g
4. In the reaction: N₂ + 3H₂ → 2NH₃, how many grams of NH₃ are produced from 3 moles of H₂?
A) 17 g
B) 34 g
C) 51 g
D) 30 g
E) 45 g
5. What is the first step in any mole-mass stoichiometry calculation?
A) Convert mass to volume
B) Balance the chemical equation
C) Measure temperature
D) Find the limiting reagent
E) Use a Bunsen burner
6. How many grams of CO₂ are produced from 2 moles of C₃H₈ in: C₃H₈ + 5O₂ → 3CO₂ + 4H₂O?
A) 44 g
B) 66 g
C) 88 g
D) 132 g
E) 264 g
7. What is the molar mass of Ca(OH)₂?
A) 56 g/mol
B) 74 g/mol
C) 40 g/mol
D) 90 g/mol
E) 100 g/mol
8. In the reaction: 2Na + Cl₂ → 2NaCl, how many grams of NaCl are formed from 3 moles of Na?
A) 117 g
B) 150 g
C) 58.5 g
D) 60 g
E) 120 g
9. What is the molar mass of CO₂?
A) 16 g/mol
B) 28 g/mol
C) 32 g/mol
D) 44 g/mol
E) 36 g/mol
10. How many grams of water are produced from 5 moles of H₂ in: 2H₂ + O₂ → 2H₂O?
A) 45 g
B) 90 g
C) 18 g
D) 72 g
E) 54 g
11. What is the correct order for a mole-mass-mole calculation?
A) Mass → Volume → Moles
B) Mass → Moles → Mole ratio → Mass
C) Moles → Volume → Mass
D) Mass → Density → Mole
E) Volume → Mass → Moles
12. In the reaction: CH₄ + 2O₂ → CO₂ + 2H₂O, how many grams of CH₄ are required to produce 88 g of CO₂?
A) 44 g
B) 22 g
C) 16 g
D) 32 g
E) 60 g
13. How many grams of Fe₂O₃ are produced when 4 moles of Fe react in: 4Fe + 3O₂ → 2Fe₂O₃?
A) 320 g
B) 159.7 g
C) 319.4 g
D) 111.2 g
E) 223 g
14. What is the mass of 2 moles of H₂O?
A) 36 g
B) 18 g
C) 72 g
D) 90 g
E) 54 g
15. What is the mass of 0.5 moles of NaCl?
A) 29.25 g
B) 58.5 g
C) 117 g
D) 24 g
E) 10 g
16. Which quantity is needed to convert between moles and mass?
A) Volume
B) Density
C) Molar mass
D) Avogadro’s number
E) Temperature
17. In: 2H₂ + O₂ → 2H₂O, how many grams of O₂ are needed to completely react with 4 moles of H₂?
A) 16 g
B) 32 g
C) 64 g
D) 48 g
E) 24 g
18. How many grams of CO₂ are produced from 2 moles of CH₄ in: CH₄ + 2O₂ → CO₂ + 2H₂O?
A) 22 g
B) 44 g
C) 88 g
D) 66 g
E) 176 g
19. What is the molar mass of NH₃?
A) 14 g/mol
B) 17 g/mol
C) 18 g/mol
D) 15 g/mol
E) 20 g/mol
20. What mass of H₂ is needed to produce 36 g of H₂O in: 2H₂ + O₂ → 2H₂O?
A) 4 g
B) 2 g
C) 6 g
D) 8 g
E) 18 g
Answers with Explanations
1. C – Mole-mass stoichiometry converts between mass and moles using molar mass and balanced equations.
2. C – 4 mol H₂ → 4 mol H₂O; 1 mol H₂O = 18 g → 4×18 = 72 g
3. A – 1 mol Al → 1 mol AlCl₃ = 133 g/mol ÷ 2 = 66.5 g
4. B – 3 mol H₂ → 2 mol NH₃ → 2×17 = 34 g
5. B – Always balance the equation first.
6. E – 2 mol C₃H₈ → 6 mol CO₂ → 6×44 = 264 g
7. B – Ca = 40, O = 16×2, H = 1×2 → 40 + 32 + 2 = 74 g/mol
8. A – 3 mol Na → 3 mol NaCl; 1 mol NaCl = 58.5 g → 3×58.5 = 117 g
9. D – C = 12, O = 16×2 → 12 + 32 = 44 g/mol
10. E – 5 mol H₂ → 5 mol H₂O = 5×18 = 90 g
11. B – That’s the correct sequence.
12. C – 1 mol CO₂ = 44 g, so 88 g = 2 mol CO₂ → needs 2 mol CH₄ = 2×16 = 32 g
13. C – 4 mol Fe → 2 mol Fe₂O₃ = 2×159.7 = 319.4 g
14. A – 1 mol H₂O = 18 g, so 2×18 = 36 g
15. A – 1 mol = 58.5 g → 0.5 mol = 29.25 g
16. C – Molar mass links grams and moles
17. B – 4 mol H₂ → 2 mol O₂ → 2×32 = 64 g
18. C – 2 mol CH₄ → 2 mol CO₂ → 2×44 = 88 g
19. B – N = 14, H = 1×3 → 14 + 3 = 17 g/mol
20. D – 2 mol H₂ → 2 mol H₂O → 2×2 = 4 g for 2 mol H₂O → for 36 g (2 mol H₂O), needs 4 g H₂ → 8 g
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