Stoichiometry and the Mole Concept Quiz

Grade 10 · Science · Quiz

Test your ability to perform mole calculations and stoichiometric conversions.

Questions

  1. How many atoms are in 2.00 moles of iron (Fe)?

    1. 6.022 × 10²³ atoms
    2. 1.204 × 10²⁴ atoms
    3. 3.011 × 10²³ atoms
    4. 2.00 atoms
    Show answer

    Answer: 1.204 × 10²⁴ atoms

    2.00 mol × 6.022 × 10²³ atoms/mol = 1.204 × 10²⁴ atoms

  2. For the reaction N₂ + 3H₂ → 2NH₃, how many moles of NH₃ are produced from 6 moles of H₂?

    1. 2 moles
    2. 3 moles
    3. 4 moles
    4. 6 moles
    Show answer

    Answer: 4 moles

    Mole ratio H₂:NH₃ is 3:2. So 6 mol H₂ × (2 mol NH₃ / 3 mol H₂) = 4 mol NH₃

  3. What is the molar mass of calcium carbonate (CaCO₃)? (Ca=40.08, C=12.01, O=16.00 g/mol)

    1. 68.09 g/mol
    2. 84.09 g/mol
    3. 100.09 g/mol
    4. 116.09 g/mol
    Show answer

    Answer: 100.09 g/mol

    CaCO₃: 40.08 + 12.01 + 3(16.00) = 40.08 + 12.01 + 48.00 = 100.09 g/mol

  4. In a reaction, 5.00 g of H₂ reacts with excess O₂ to form water. What mass of water is produced? (H₂=2.016, H₂O=18.016 g/mol)

    1. 18.0 g
    2. 44.7 g
    3. 9.0 g
    4. 90.1 g
    Show answer

    Answer: 44.7 g

    5.00 g H₂ ÷ 2.016 g/mol = 2.48 mol H₂. Ratio H₂:H₂O is 1:1 (2H₂+O₂→2H₂O gives 1:1). 2.48 mol × 18.016 g/mol ≈ 44.7 g

  5. A student obtains 4.50 g of product when the theoretical yield is 5.00 g. What is the percent yield?

    1. 45.0%
    2. 80.0%
    3. 90.0%
    4. 95.0%
    Show answer

    Answer: 90.0%

    % yield = (4.50 g ÷ 5.00 g) × 100% = 90.0%

  6. Which statement best defines the limiting reactant?

    1. The reactant present in the smallest mass
    2. The reactant with the lowest molar mass
    3. The reactant that is completely consumed and determines the maximum product
    4. The reactant added first to the reaction vessel
    Show answer

    Answer: The reactant that is completely consumed and determines the maximum product

    The limiting reactant is completely consumed and its amount determines how much product can form

  7. A compound with empirical formula CH₂ and molecular mass of 42 g/mol has a molecular formula of C₃H₆.

    Show answer

    Answer: True

    Empirical formula mass of CH₂ = 14 g/mol. 42 ÷ 14 = 3, so molecular formula = C₃H₆

  8. The number 6.022 × 10²³ is known as _________ number.

    Show answer

    Answer: avogadro's

    Avogadro's number (6.022 × 10²³) honors Amedeo Avogadro and represents the number of particles per mole

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