Chapter 4, Problem 4.43PAE

4.43 Magnesium nitride forms in a side reaction when magnesium metal burns in air. This reaction may also be carried out in pure nitrogen.

   $\text{3 Mg}\left(\text{s}\right)+{\text{ N}}_{\text{2}}\left(\text{g}\right)\to {\text{ Mg}}_{\text{3}}{\text{N}}_{\text{2}}\left(\text{s}\right)$

If 18.4 g of Mg₃N₂forms from the reaction of 20.0 g of magnesium with excess nitrogen, what is the percentage yield?