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Reviewed CSCA Chemistry question · Easy

How many moles of oxygen atoms are present in 22.0 g of carbon dioxide (CO2)? (Molar masses: C = 12.0 g/mol, O = 16.0 g/mol)

  1. 0.50 mol
  2. 1.0 mol
  3. 1.5 mol
  4. 2.0 mol
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Correct answer

B. 1.0 mol

Principle or equation

Moles of compound = mass / molar mass. Each mole of CO2 contains 2 moles of oxygen atoms.

Why this answer is correct

Molar mass of CO2 = 12.0 + 2(16.0) = 44.0 g/mol. Moles of CO2 = 22.0 g / 44.0 g/mol = 0.50 mol. Oxygen atoms = 0.50 mol × 2 = 1.0 mol.

Example

For 11.0 g CO2, moles = 0.25 mol, oxygen atoms = 0.50 mol.

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