Question

this is the chemical formula for calcium phosphate: $ca_{3}(po_{4})_{2}$. calculate the mass percent of phosphorus in calcium phosphate. round your answer to the nearest percentage.

Explanation:

Step1: Determine atomic masses

Atomic mass of Ca = 40.08 g/mol, P = 30.97 g/mol, O = 16.00 g/mol.

Step2: Calculate molar mass of $Ca_3(PO_4)_2$

Molar mass = $3\times40.08+2\times(30.97 + 4\times16.00)$
$=120.24+2\times(30.97 + 64.00)$
$=120.24+2\times94.97$
$=120.24 + 189.94$
$=310.18$ g/mol

Step3: Calculate mass of P in $Ca_3(PO_4)_2$

Mass of P = $2\times30.97=61.94$ g/mol

Step4: Calculate mass - percent of P

Mass - percent of P = $\frac{61.94}{310.18}\times100\%$
$\approx 19.97\%$
Rounding to the nearest percentage gives 20%.

Answer:

20%