Question

Need Help! I have no clue.

Commercial manufacturers produce nitric acid (HNO_3) by the Ostwald process. The process consists of three steps as follows.

4NH_3(g) + 5O_2(g) = 4NO(g) + 6H_2O(g)

2NO(g) + O_2(g) = 2NO_2(g)

3NO_2(g) + H_2O(l) = 2HNO_3(aq) + NO(g)

You begin with 37.0 kg of ammonia (NH_3) and an unlimited supply of dioxygen and water.

a.) How many kilogram of Oxygen gas will be consumed in the process?

b.)If the reaction normal has a percent yield of 83.0%, how many kilograms of nitric acid will actually be produced?

Answer 1

I know this problem seems daunting, but I will help you. I will provide steps I would like for you to take to solve the problem with an explanation as to why you are doing it.
First and foremost, make sure you are familiar with the process of working with dimensional units, as working in this manner will help you keep track of critical conversions, such as molar ratios.

Part a
First, you must find the number of moles in 37kg of NH3-there exists a relationship between NH3 and O2 as given above, so we need to know how much material we are working with
-dimensional analysis/unit conversion
-conversion of mass to moles

Second, we know that there are a total of 6 moles of O2 consumed is consumed in the reaction(we got this by adding the O2s up on the reagent sides). Find the ratio of NH3/O2 and apply it to the moles of NH3 you found in the first step.(using stoichiometry)
-Now we know how many moles of O2 are consumed in the reaction

Third, convert the amount you found in the second step back into kilograms.
-convert moles to mass
-unit conversion from g to kg.

Now you have your solution.

Part b
First, find the # of moles that are in 37kg of NH3-this will eventually become our product!!!
-dimensional analysis/unit conversion
-conversion of mass to moles

Second, solve the first reaction equation by using stoichiometry
-You have xmolsNH3, find the ratio of NH3/NO
-apply that ratio to the amount of NH3 you have to find how much NO is produced

Third, repeat the second step for the remaining reaction equations to find the amount of HNO3 formed
-make sure to keep track of only the nitrogen containing species!

Fourth, convert your product from moles back to kilograms
-conversion of moles to mass
-dimensional analysis/unit conversion

What do you have now? You have the THEORETICAL yield of these reactions. Now, if the problem assumes that you have a yield of 83.0% OVERALL, then you can just take the product of the percentage and the theoretical yield.

Now you should have your solution