Now, let's add complexity with a limiting reagent.
Reaction: N₂ + 3H₂ → 2NH₃
You start with 14 g of N₂ and 6 g of H₂. Which is the limiting reagent and what's the theoretical yield?
1 Moles of N₂ = 14 ÷ 28 = 0.5 mol
2. Moles of H₂ = 6 ÷ 2 = 3 mol
3. Reaction needs 3 mol H₂ per 1 mol N₂. For 0.5 mol N₂, you'd need 1.5 mol H₂. You actually have 3 mol H₂, so H₂ is in excess. N₂ is limiting.
4. Equation: 1 mol N₂ → 2 mol NH₃.
0.5 mol N₂ → 1.0 mol NH₃
5. Molar mass of NH₃ = 17 g/mol
1.0 × 17 = 17 g of NH₃
So the theoretical yield of a reaction depends entirely on the limiting reagent.