4 NH3 (g) + 5 O2 (g) → → 4 NO (g) + 6 H2O (l) How many moles of NH3 is required to produce 25.9 grams of NO?

Answer 1

Kendra,

Since the balanced equation provides the mole ratios between the different substances involved, it's important that our units are moles before we begin to use it. We have to use the equation because it's the only thing that connects the 2 things we're interested in.

Begin by converting 25.9 g NO to moles by using NO's molar mass

25.9 g x 1 mole/30.0061 g = 0.863 moles NO

Now we can use the relationship between NH₃ and NO shown in the balanced equation:

4 mols NH₃ : 4 mols NO

There is an equal ratio between them (4:4), so whatever number of moles of NO we get it's coming from an equal number of moles of NH₃.