What is the molar mass of Al₂O₃? (H = 1, C = 12, N = 14, O = 16, Na = 23, Mg = 24, Al = 27, S = 32, Cl = 35.5, K = 39, Ca = 40, Mn = 55, Fe = 56)

Answer and explanation

Correct answer: B. 102 g/mol

  1. Step 1: Add the atomic masses of all the atoms in the formula. Step 2. Al₂O₃: 2 × 27 + 3 × 16 = 102 g/mol. Answer: 102 g/mol. Why not the others: 64 g/mol is what you get if you use the molar mass of SO₂. 44 g/mol is what you get if you use the molar mass of CO₂. 106 g/mol is what you get if you use the molar mass of Na₂CO₃.

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