The balanced chemical equation for the formation of sodium azide is as given below:
NaNO3+3NaNH2⟶NaN3+3NaOH+NH3
15.0 g sodium nitrate corresponds to 15.085=0.1765moles.
15.0 g of sodamide corresponds to 15.039=0.385moles.
Hence, sodamide is the limiting reagent.
0.385 moles of sodamide will produce 0.3853=0.128moles of sodium azide.
The mass of sodium azide produced will be 0.128×65=8.3g.
Hence, 8 g of NaN3 is produced.