Question

how many liters of NH3 at STP will react with 15.9 grams of O2 to form NO2 and water

Answer 1

1. Form your equation and balance it
\(NH_{3}\ +\ 7O_{2}→4NO_{2}+6H_{2}O\)
2. Use Dimensional Analysis
\(15.9\ g\ O_{2}\ \cdot\ \frac{1\ mol\ O_{2}}{32\ g\ O_{2}}\cdot\frac{1\ mol\ NH_{3}}{7\ mol\ O_{2}}\cdot\frac{22.4\ L\ NH_{3}}{1\ mol\ NH_{3}}\)

Answer 2

Keep in mind that I used 22.4L/1 mol because it's at STP. Otherwise you'll then need to stop and go to ideal gas law.