Question 3 • LA-Chemistry A
Al₂(SO₄)₃ contains 2 aluminum atoms, 3 sulfur atoms, and 12 oxygen atoms. Using atomic masses of about 26.98 g/mol for Al, 32.06 g/mol for S, and 16.00 g/mol for O gives 2(26.98) + 3(32.06) + 12(16.00) = 342.14 g/mol, which rounds to 342.17 g/mol with more precise atomic masses. Therefore, the molar mass is choice C, 342.17 g/mol.
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