What is the mass of sulfur atoms in 0.400 mol of aluminum sulfate, Al2(SO4)3? (Molar masses: Al = 27.0 g/mol, S = 32.1 g/mol, O = 16.0 g/mol)
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Correct answer
A. 38.5 g
Principle or equation
One mole of Al2(SO4)3 contains 3 moles of sulfur atoms. Use the molar ratio and molar mass of sulfur to find the mass.
Why this answer is correct
Moles of S = 0.400 mol Al2(SO4)3 × 3 = 1.20 mol S. Mass = 1.20 mol × 32.1 g/mol = 38.5 g.
Example
For 0.200 mol of Na2SO4, moles of S = 0.200 mol, mass = 0.200 × 32.1 = 6.42 g.
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