When 0.406 moles of nitrogen react with sufficient hydrogen, how many moles of ammonia (NH3) are formed?

Answer 1

Balanced reaction:

N2 (g) + 3 H2 (g) → 2 NH3 (g)

0.406 mol N2 → ? mol NH3

Mole ratio from the balanced chemical reaction is that for every 1 mole of N2 that reacts, 2 moles of NH3 are formed.

0.406 mol N2 x (2 mol NH3 / 1 mol N2) = 0.812 mol NH3

Question #2

Use the mole ratio from above to first convert mol N2 to mol NH3.

0.186 mol N2 x (2 mol NH3 / 1 mol N2) = 0.372 mol NH3

MW of NH3 = 17.03 g / mol

0.372 mol NH3 x (17.03 g NH3 / 1 mol NH3) = 6.34 g NH3

Question #3

Stoichiometry conversion

g NH3 → mol NH3 → mol H2 → g H2

50.0 g NH3 x (1 mol NH3 / 17.03 g NH3) x (3 mol H2 / 2 mol NH3) x (2.02 g H2 / 1 mol H2) = 8.90 g H2 needed