Question

When magnesium burns in air, it reacts with oxygen and nitrogen, forming magnesium oxide and magnesium nitride. If 20.0L of air is available for this reaction, what mass of each compound can be formed? (Remember air is about 80% Nitrogen and 20% Oxygen)

Answer 1

2Mg + O2 ==> 2MgO
3Mg + N2 ==> Mg3N2
20 mL air x 0.80 N2 = 16 mL N2
20 mL air x 0.20 O2 = 4 mL O2.
I assume we are dealing with STP conditions; therefore,
mols N2 = 16/22.4 = ? and convert that to mols Mg3N2 then to grams. g = mols x molar mass.

mols O2 = 4/22.4 = ? and convert to mols MgO, then to grams.

Total = g MgO + grams Mg3N2.