What is the molar mass of Ca3(PO4)2 (approximately)?

• A. 310.18 g/mol (approximately)
• B. 296.18 g/mol (approximately)
• C. 322.20 g/mol (approximately)
• D. 299.00 g/mol (approximately)

Answer: (A)

Calculating molar mass means adding up the masses of all atoms in one formula unit, using how many of each atom appear in the formula. For Ca3(PO4)2, there are three calcium atoms, two phosphate groups (each with one phosphorus and four oxygens).

Three calcium atoms contribute 3 × 40.08 = 120.24 g/mol.

Two phosphorus atoms contribute 2 × 30.97 = 61.94 g/mol.

Eight oxygen atoms contribute 8 × 16.00 = 128.00 g/mol.

Sum: 120.24 + 61.94 + 128.00 = 310.18 g/mol.

So the molar mass is about 310.18 g/mol, which matches the given approximate value. Variations like around 296, 299, or 322 g/mol would come from miscounting atoms or using rougher masses.