01Grams → moles → moles → grams
Convert to moles, use the coefficient ratio, convert back. Find the limiting reactant by seeing which produces less product.
Percent yield = actual ÷ theoretical × 100.
02Notebook box
g A → mol A → (ratio) → mol B → g B.
Worked example: 4.0 g H₂ with excess O₂ → 2 mol H₂ → 2 mol H₂O → 36 g H₂O.