Question

Calculate the mass percent of calcium, phosphorus and oxygen in calcium phosphate $$\mathrm{Ca}{\phantom{A}}_3(\mathrm{PO}{\phantom{A}}_4){\phantom{A}}_2$$.

Answer 1

Molecular mass of $$\mathrm{Ca}{\phantom{A}}_3(\mathrm{PO}{\phantom{A}}_4){\phantom{A}}_2$$ = 310.18 g/mole

Given mass of calcium = 4 × 30 = 120 g

Given mass of phosphorous = 31 × 2 = 62 g

Given mass of oxygen = 16 × 8 = 128 g

Mass percent of calcium = ${\displaystyle \frac{120}{310.18}\times 100}$ = 38.71%

Mass percent of phosphorous = ${\displaystyle \frac{62}{310.18}\times 100}$ = 20%

Mass percent of oxygen = ${\displaystyle \frac{128}{310.18}\times 100}$ = 41.29%