Question

Find the percentage of Phosphorus in
(i) Calcium hydrogen Phosphate
(ii) Calcium Phosphate

Answer 1

Percentage of phosphorus in -

(i) Calcium hydrogen Phosphate - 22.78 %

(ii) Calcium Phosphate - 19.98 %

Percentage of any element is given by the formula- (Atomic Mass of Element)/(Molecular Mass of the Compound)*100

Mass of phosphorus is 31 g/mol.

Calcium hydrogen phosphate is represented by the chemical formula - CaHPO₄

Molecular weight of compound is - 136.06 g/mol

Percentage of phosphorus is calculated by the formula-

(31/136.06)*100

22.78 %

Calcium phosphate is represented by the chemical formula- Ca3(PO4)2

Molecular weight of compound is - 310.18 g/mol

Percentage of phosphorus is calculated by the formula-

(31/310.18)*100

9.99 %

Number of atoms in given molecule is 2

Thus, percentage of phosphorus in molecule will be - 9.99*2

19.98 %