25 g of calcium carbonate reacts completely according to CaCO → CaO + CO. What mass of calcium oxide is formed? (Relative masses: calcium carbonate 100, calcium oxide 56.)
Answer and explanation
Correct answer: A. 14 g
- Step 1: Moles of calcium carbonate mol.
- Step 2: From the equation, 1 mol of calcium carbonate gives 1 mol of calcium oxide, so moles of calcium oxide mol.
- Step 3: Mass g.
Answer
14 g.
Why not the others: 25 g: it assumes mass is conserved between reactant and product alone. 28 g: it doubles the correct value.
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