Question

What is gas stoichiometry?

Answer 1

Gas stoichiometry is the study of the relative amounts of reactants and products in reactions that involve gases.

EXAMPLE
Calculate the volume of gaseous NO₂ produced by the combustion of 100 g of NH₃ at 0°C and 100 kPa.

Solution

Step 1. Write the balanced chemical equation.

4NH₃(g) + 7O₂(g) → 4NO₂(g) + 6H₂O(l)

Step 2. Convert mass of NH₃ → moles of NH₃ → moles of NO₂.

100 g NH₃ × `(1"mol NH"_3)/(17.03"g NH"_3) × (4"mol NO"_2)/(4"mol NH"_3)` = 5.872 mol NH₃ (3 significant figures +
1 guard digit)

Step 3. Use the Ideal Gas Law to calculate the volume of NO₂.

`PV = nRT`

`V = (nRT)/P = (5.872"mol" × 8.314"kPa·L·K"^-1"mol"^-1 × 273"K")/(100 "kPa")` = 133 L