Nitric acid is a key industrial chemical, largely used to make fertilizers and explosives. The first step in its synthesis is the oxidation of ammonia. In this reaction, gaseous ammonia reacts with dioxygen gas to produce nitrogen monoxide gas and water. Suppose a chemical engineer studying a new catalyst for the oxidation of ammonia reaction finds that 645. liters per second of dioxygen are consumed when the reaction is run at 195.oC and 0.88 atm. Calculate the rate at which nitrogen monoxide is being produced. Give your answer in kilograms per second. Be sure your answer has the correct number of significant digits.

The answer is 0.36 kg/s NO

Explanation:

the chemical reaction of NH3 to NO is as follows:

4NH3(g) + 5O2(g) ⟶4 NO(g) +6 H2O(l)

We have the following data:

O2 Volume rate = 645 L/s

P = 0.88 atm

T = 195°C + 273 = 468 K

NO molecular weight = 30.01 g/mol  

we calculate the moles found in 645 L of O2:

P*V = n*R*T

n = P*V/R*T

n= (0.88 atm * 645L/s)/((0.08205 L*atm/K*mol) * 468 K) = 14.78 moles of O2

With the reaction we can calculate the number of moles of NO and with its molecular weight we will have the rate of NO:

14.78 moles/s O2 * 4 molesNO/5 molesO2 * 30.01 g NO/1 molNO x 1 kgNO/1000 gNO = 0.36 kg/s NO

i believe you are right for all except the 3rd ( look at sqdancefan his answer is much better)