Question

Calculate the percent composition by mass (to 4 significant figures) of all the elements in calcium phosphate [Ca3(PO4)2], a major component of bone.

Answer 1

Answer:

The elements present in calcium phosphate-based on molecular formula are calcium, phosphorus, and oxygen. The molecular mass of Ca or calcium is 40.08 grams per mole, the molecular mass of P or phosphorus is 30.97 grams per mole, and the molecular mass of oxygen is 16.00 grams per mole. So, in combination, the molecular mass of Ca₃(PO₄)₂ is, = (3 × 40.08 + 2 ×3 0.97 + 8 × 16) = 310.18 grams per mole

Now, the mass percent of calcium is, = n × molecular mass of calcium/ molecular mass of Ca₃(PO₄)₂ × 100% = 3 × 40.08 / 310.18 × 100 = 38.76 % Thus, the mass percent of the calcium in calcium phosphate is 38.76%.  

The mass percent of phosphorus (P), = n × molecular mass of phosphorus/molar mass of Ca₃(PO₄)₂ × 100% = 2 × 30.97/310.18 × 100 = 19.97% Thus, the mass percent of phosphorus in calcium phosphate is 19.97%.  

The mass percent of oxygen (O), = n × molecular mass of oxygen/molar mass of Ca₃(PO₄)₂ × 100% = 8 × 16/310.18 × 100% = 41.27% Thus, the mass percent of oxygen in calcium phosphate is 41.27%.