Ammonia reacts with oxygen at 120 C to form NO and H20 in a sealed 40-L container. When 34 g of ammonia reacts with 96 g of oxygen, what is the partial pressure of the NO? What is the total pressure?

Answer 1

Write and balance the equation.
This is a limiting reagent problem.
Convert 34 g NH3 to mols. mols = g/molar mass.
Convert 96 g O2 to mols.
Using the coefficients in the balanced equation, convert mols NH3 to mols NO.
Do the same for O2.
It is likely that you will obtain two different answers; the correct answer in limiting reagent problems is ALWAYS the smaller one and the reagent producing that value is the limiting reagent.
Using the limiting reagent value do the following:
a. Calculate mols H2O formed.
b. Calculate mols of the non-limiting reagent used.
c. Subtract mols non-limiting reagent initially less mols used to determine mols remaining unreacted.
Then use PV = nRT to solve for pressure of each gas at the conditions listed. Add all of them to find the total pressure.
Post your work if you get stuck.