Answer:
a. 77%
Explanation:
To solve the exercise, you need to know the limiting reagent. The limiting reagent is one that is consumed first in the chemical reaction. The other reagent is known as an excess reagent, and it is the one left over in a chemical reaction.
To know if ammonia or oxygen is the limiting reagent, we should relate the weights of both compounds in the reaction. We know that 4NH3 (68 g) react with 5O2 (160 g), so we should find out how much NH3 is required to react with 150 g of O2:
160 g O2 _______ 68 g NH3
150 g O2 _______ x = 150 g * 68 g / 160 g = 63.75 g NH3
As we have 150 g of NH3 but only 63.75 g are required, we know that ammonia is the excess reagent, so oxygen is the reagent that limits the reaction and that we should use to calculate the percentage yield of the reaction.
In the reaction we observe that 5O2 (160 g) produces 4NO (120g), so:
160 g O2 ______ 120 g NO
150 g O2 ______ x = 150 g * 120 g / 160 g = 112.5 g NO
If the percent yield of the reaction were 100%, it would produce 112.5 g of NO, however only 87 g of NO were obtained, so we should find out what the percentage of reaction yield was:
112.5 g NO ______ 100%
87 g NO _______ x = 87g * 100% / 112.5 g = 77%
Thus we observe that the reaction had a yield of 77%.
