Question

Calculate the percentage composition of Ca₃(PО₄)₂.

[At. wts. are O = 16, Ca = 40, P = 31]

Answer 1

Mol. wt. of Ca₃(PО₄)₂ = 3 [At. wt. of Ca] + 2 [At. wt. of P] + 8 [At. wt. of O]

= 3 × 40 + 2 × 31 + 8 × 16

= 120 + 62 + 128

= 310 amu

Percentage of Calcium (Ca) = `120/310 xx 100` = 38.71%

Percentage of Phosphorus (P) = `62/310 xx 100` = 20.00%

Percentage of Oxygen (O) = `128/310 xx 100` = 41.29%