Final Answer:
11.55 grams of iron
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Explanation:
Let’s solve this step by step like we’re cooking with a recipe — but with chemicals!
We have this reaction:
Fe₂O₃ + 3H₂ → 2Fe + 3H₂O
This means:
1 “piece” (molecule) of Fe₂O₃ makes 2 “pieces” (atoms) of Fe.
But we don’t count molecules in real life — we weigh them in grams. So we need to convert grams to moles, then use the recipe (the balanced equation), then convert back to grams.
Step 1: Find the molar mass of Fe₂O₃
- Iron (Fe) = 55.85 g/mol → 2 atoms = 2 × 55.85 = 111.7 g
- Oxygen (O) = 16.00 g/mol → 3 atoms = 3 × 16.00 = 48.0 g
→ Total = 111.7 + 48.0 = 159.7 g/mol
Step 2: Convert 16.5 grams of Fe₂O₃ to moles
→ Moles = mass ÷ molar mass = 16.5 ÷ 159.7 ≈ 0.1033 moles
Step 3: Use the recipe (stoichiometry)
From the equation: 1 mole Fe₂O₃ → 2 moles Fe
So, 0.1033 moles Fe₂O₃ → 2 × 0.1033 = 0.2066 moles Fe
Step 4: Convert moles of Fe to grams
Molar mass of Fe = 55.85 g/mol
→ Mass = moles × molar mass = 0.2066 × 55.85 ≈ 11.55 grams
✔ So, from 16.5 grams of rust (Fe₂O₃), you can make about 11.55 grams of pure iron.
You did it! Just follow the steps: grams → moles → use ratio → moles → grams. Like a recipe!
Parent Tip: Review the logic above to help your child master the concept of stoichiometry review worksheet.
