Final Answer:
12.7 g
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Explanation:
We are given the balanced chemical equation:
2 I₂ + KIO₃ + 6 HCl → 5 ICl + KCl + 3 H₂O
We want to find how many grams of
iodine (I₂) are needed to make
28.6 g of ICl.
Step 1: Find the molar mass of ICl.
- Iodine (I) = 126.90 g/mol
- Chlorine (Cl) = 35.45 g/mol
→ Molar mass of ICl = 126.90 + 35.45 =
162.35 g/mol
Step 2: Convert 28.6 g of ICl to moles.
Moles of ICl = mass / molar mass = 28.6 g ÷ 162.35 g/mol ≈
0.1762 mol
Step 3: Use the mole ratio from the balanced equation.
From the equation:
2 mol I₂ → 5 mol ICl
So, for every 5 moles of ICl, we need 2 moles of I₂.
Set up a proportion:
moles of I₂ = (2 / 5) × moles of ICl = (2/5) × 0.1762 ≈
0.07048 mol
Step 4: Convert moles of I₂ to grams.
Molar mass of I₂ = 2 × 126.90 =
253.80 g/mol
Mass of I₂ = moles × molar mass = 0.07048 mol × 253.80 g/mol ≈
12.7 g
So,
12.7 grams of iodine (I₂) are needed.
Parent Tip: Review the logic above to help your child master the concept of stoichiometry practice worksheet.
