What is the mass of 0.150 mol of calcium phosphate, Ca3(PO4)2? (Molar masses: Ca = 40.1 g/mol, P = 31.0 g/mol, O = 16.0 g/mol)
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Correct answer
A. 46.5 g
Principle or equation
Molar mass of a compound is the sum of the atomic masses of all atoms in the formula. Mass = amount (mol) × molar mass.
Why this answer is correct
Molar mass of Ca3(PO4)2 = 3(40.1) + 2[31.0 + 4(16.0)] = 120.3 + 2(95.0) = 120.3 + 190.0 = 310.3 g/mol. Mass = 0.150 mol × 310.3 g/mol = 46.545 g ≈ 46.5 g.
Example
For 0.200 mol of Na2CO3 (molar mass 106 g/mol), mass = 21.2 g.
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