What volume (L) of NH3 gas at STP is produced by the complete reaction of 7.5 g of H2O acording to the following reaction.

Question

MgN2(s) + 6H2O(l) → 3Mg(OH)2(aq) + 2NH3(g)

9.3

3.1

28

19

Answer 1

First convert g of H₂O to mol NH₃ using stoichiometry. From the balanced reaction, 6 moles of H₂O reacts to form 2 moles of NH₃. The mole ratio of H2O to NH₃ is 6:2.

7.5 g H₂O x (1 mol H₂O / 18.02 g H₂O) x (2 mol NH₃ / 6 mol H₂O) = 0.14 mol NH₃

Next, at STP, 1 mole of a gas occupies a volume of 22.4 L.

Vol. of NH₃ produced = 0.14 mol x (22.4 L / 1 mol) = 3.1 L (answer choice b)