Stoichiometry for gas volume and particle counts

Answer Key - Grade 10 Science Worksheet

Circle the best answer, or write your answer on the line.

1. 1.

   50 g of CaCO₃ (molar mass 100.09 g/mol) breaks down: CaCO₃ → CaO + CO₂. What volume of CO₂ forms at STP, using 22.4 L/mol, Ari?

   11.19 L
2. 2.

   25 g of CaCO₃ (molar mass 100.09 g/mol) breaks down: CaCO₃ → CaO + CO₂. What volume of CO₂ forms at STP, using 22.4 L/mol, Bo?

   5.59 L
3. 3.

   10 g of CaCO₃ (molar mass 100.09 g/mol) breaks down: CaCO₃ → CaO + CO₂. What volume of CO₂ forms at STP, using 22.4 L/mol, Esme?

   2.24 L
4. 4.

   In 2 H₂ + O₂ → 2 H₂O, how much O₂ reacts with 44.8 L of H₂ at STP, Jun?

   • 44.8 L
   • 22.4 L
   • 89.6 L
5. 5.

   In N₂ + 3 H₂ → 2 NH₃, 1 mol of N₂ reacts fully. What volume of NH₃ forms at STP, Kira?

   • 22.4 L
   • 44.8 L
   • 67.2 L
6. 6.

   Why can gas volumes at the same T and P use the mole ratio directly, Luz?

   • Gases weigh the same per liter
   • Gases don't follow ratios
   • Equal volumes hold equal moles
7. 7.

   How many water molecules are in 2 mol of water, Milo?

   • 6.022 × 10²³
   • 1.204 × 10²⁴
   • 3.011 × 10²³
8. 8.

   How many atoms in all are in 1 mol of NH₃ molecules, Pia?

   • 1 × 6.022 × 10²³
   • 3 × 6.022 × 10²³
   • 4 × 6.022 × 10²³
9. 9.

   Which standard does this sheet use for gas volumes, Tala?

   • 0 °C and 1 atm: 22.4 L/mol
   • 0 °C and 1 atm: 1 L/mol
   • 25 °C and 1 atm: 22.4 L/mol
10. 10.

    Which route turns molecules of one substance into molecules of another, Zee?

    • ÷ molar mass, × ratio, × 22.4
    • ÷ 6.022 × 10²³, × ratio, × 6.022 × 10²³
    • × 22.4, × ratio, ÷ 22.4