Final volume of Argon gas: 6. Volume-Volume Problem: If water vapor is added to Magnesium Nitride, ammonia gas is produced
when the mixture is heated, according to the following reaction:
Mg3N2 (s) +
H2O (g)—->
Mgo (s) +
NH3 (g)
If 10.2 mL of water reacts with magnesium nitride, what volume (in Liters) of Ammonia gas will form at
STP?

6.78 × 10⁻³ L

Explanation:

Step 1: Write the balanced equation

Mg₃N₂(s) + 3 H₂O(g) ⇒ 3 MgO(s) + 2 NH₃(g)

Step 2: Calculate the moles corresponding to 10.2 mL (0.0102 L) of H₂O(g)

At STP, 1 mole of H₂O(g) has a volume of 22.4 L.

0.0102 L × 1 mol/22.4 L = 4.55 × 10⁻⁴ mol

Step 3: Calculate the moles of NH₃(g) formed from 4.55 × 10⁻⁴ moles of H₂O(g)

The molar ratio of H₂O to NH₃ is 3:2. The moles of NH₃ produced are 2/3 × 4.55 × 10⁻⁴ mol = 3.03 × 10⁻⁴ mol.

Step 4: Calculate the volume corresponding to 3.03 × 10⁻⁴ moles of NH₃

At STP, 1 mole of NH₃(g) has a volume of 22.4 L.

3.03 × 10⁻⁴ mol × 22.4 L/mol = 6.78 × 10⁻³ L