Question

Calculate the mass percent of calcium, phosphorus and oxygen in calcium phosphate Ca3(PO4)2.

Answer 1

Ca3( PO4)2

atomic mass of calcium ( Ca) = 40 g/mol
atomic mass of phosphorus ( P) = 31 g/mol
atomic mass of Oxygen ( O) = 16 g/mol
molecular mass of C3(PO4)2 = 3 × 40 + 2× (31+ 64) = 120 + 2 × 95 = 120 + 190
= 310 g/mol

now,

% of Ca in Ca3(PO4)2 = 3×40/310 × 100
= 1200/31 % = 38.7 %

% of P in Ca3(PO4)2 = 2×31/310 × 100
= 20 %

% of O in Ca3(PO4)2 = 8 × 16/310 × 100
= 1280/31 = 41.3 %

Answer 2

Atomic mass of calcium (Ca) = 40

Atomic mass of phosphorus (P) = 31.

Atomic mass of oxygen (O) = 16.

Now, molecular mass of calcium phosphate = 40 (3) + (31+64)2 = 120 + 95(2) = 120+190 = 310 g/mol.

Percentage of Ca in Ca3(PO4)2 = 40(3)/310 ×100 = 120/310 ×100 = 38.7....%

Percentage of P in Ca3(PO4)2 = 31(2)/310 ×100 = 20%

Percentage of O in Ca3(PO4)2 = 16(4)(2)/310 ×100 = 128/310 ×100 = 41.29..%

:)