Synthesis of ammonia chemistry equation

Question

The synthesis of ammonia is given below: H2+N2 =NH3

calculate the mass in grams of nitrogen gas required to form 1.43kg of ammonia gas.

relative atomic masses: hydrogen = 1; nitrogen = 14

Answer 1

First, write a correctly balanced equation:

3H₂ + N₂ ==> 2NH₃

If we want to make 1.43 kg of NH₃ gas, we will first convert that to moles, so that we can then determine the moles of N₂ gas required to make that amount. Molar mass NH₃ = 14+3 = 17 g/mole.

moles of NH₃ made = 1.43 kg x 1000 g/kg x 1 mole/17 g = 84.12 moles NH₃ desired

moles N₂ needed: molar mass N₂ = 14+14 = 28 g/mole. Since the balanced equation tells us that for every 2 moles of NH₃ made, we will need 1 mole of N₂ gas. Thus, 84.12 moles NH₃ x 1 mole N₂/2 mol NH₃ = 42.06 moles N₂ needed. Now we will convert this to grams of N₂.

42.06 moles N₂ x 28 g/mole = 1178 g N₂ = 1180 g N₂ (to 3 significant figures)