What mass of calcium carbonate (GFM 100) is needed to make 2.2 g of carbon dioxide (GFM 44) by CaCO₃ → CaO + CO₂?
Answer and explanation
Correct answer: A. 5 g
- Step 1: Moles of CO₂ = 2.2 ÷ 44 = 0.05 mol.
- Step 2: The ratio CaCO₃ : CO₂ is 1 : 1, so 0.05 mol of CaCO₃ is needed.
- Step 3: Mass = 0.05 × 100 = 5 g.
Answer
5 g.
Why not the others: 2.2 g: the masses of reactant and product are not equal. 100 g: this is the mass of 1 mol. 0.05 g: the moles were not converted to mass.
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