So to find the limiting reagent and excess reagents you would first convert from grams to moles. From there you would find that the mole to mole ratio of Nitrogen to Hydrogen is 1:3. Then you would find that after using all moles of Nitrogen you would still have 6 moles of Oxygen (I rounded from the beginning). Making Nitrogen the limiting reagent and Hydrogen the excess reagent. Then using atomic weight of Ammonia which is 15.018 g/mole you would figure out how much Ammonia was made by using 54 moles (using ratio) and multiplying that by 15.018 (atomic weight). Then I got 810.972 grams. I’m not sure if this is completely correct but I will include my work to help you.