Hint 2-61

First read section 3.7 of your text book.

Check the equation is balanced.

Determine the actual number of moles of both reagents. (n = m/M).

Divide all the coefficients in the balanced equation by 4 so that the
equation reflects what 1 mol of NH₃ does in the reaction.

Work out how many moles of O₂ are needed (assisted by the equation),
this is the ideal number of moles.

Compare the ideal number of moles of O₂ with the actual number of
moles of O₂ that are present.

If the actual number of moles is smaller than the ideal moles of O₂
then O₂ is limiting, if not NH₃ is limiting.