What is the number of moles of h2o formed when 2.0 moles of NH3 react completely

(1) Moles of O2 (g) needed to completely react with 2.00 moles of NH3 (g).

4NH3 (g) + 5O2 (g) → 4NO (g) + 6H2O (g)

-Use a conversion factor fraction.

-Start with moles of NH3, then the molar ratio of O2 to NH3.

[2 mol NH3/1] x [5 mol O2 / 4 mol NH3] = 2.5 moles of O2

(as you can see, the variable of mol NH3 cancel out leaving mol O2)