Stoichiometry for gas volume and particle counts

Answer Key - Grade 10 Science Worksheet - Challenge Me

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

1. 1.

   In 2 H₂ + O₂ → 2 H₂O, 11.2 L of O₂ at STP reacts (22.4 L/mol). How many water molecules form, in units of 10²³ (1 mol = 6.022 × 10²³), Ari?

   6.02 × 10²³ molecules
2. 2.

   In 2 H₂ + O₂ → 2 H₂O, 5.6 L of O₂ at STP reacts (22.4 L/mol). How many water molecules form, in units of 10²³ (1 mol = 6.022 × 10²³), Bo?

   3.01 × 10²³ molecules
3. 3.

   100.09 g of CaCO₃ breaks down to CaO and CO₂. How many CO₂ molecules form, Kira?

   • 1.204 × 10²⁴
   • 6.022 × 10²³
   • 100.09 × 10²³
4. 4.

   What is the mass of 44.8 L of CO₂ at STP (44.01 g/mol), Luz?

   • 88.02 g
   • 44.8 g
   • 44.01 g
5. 5.

   Milo says 22.4 L of O₂ at STP is 22.4 mol. Agree or disagree?

   • Agree: liters and moles are the same
   • Agree: O₂ has 22.4 per liter
   • Disagree: it is 1 mol
6. 6.

   Noah says 11.2 L of H₂ at STP holds 11.2 × 6.022 × 10²³ molecules. Agree or disagree?

   • Disagree: 11.2 L is 0.5 mol
   • Agree: each liter is a mole of molecules
   • Agree: H₂ is the lightest gas
7. 7.

   Pia says 1 mol of CO₂ fills more space than 1 mol of H₂ at STP because CO₂ is heavier. Agree or disagree?

   • Agree: CO₂ molecules spread wider
   • Disagree: both fill 22.4 L
   • Agree: heavier gases fill more
8. 8.

   A sheet uses IUPAC's 100 kPa standard, 22.7 L/mol. What volume do 2 mol of gas fill, Ren?

   • 44.8 L
   • 22.7 L
   • 45.4 L
9. 9.

   Why must a sheet say which standard it uses for gas volumes, Tala?

   • Moles change with the weather
   • Gases change mass at each standard
   • Molar volume depends on T and P
10. 10.

    What volume does 0.25 mol of gas fill at STP (0 °C and 1 atm), Zee?

    • 89.6 L
    • 5.6 L
    • 0.25 L