• # question_answer 71)   Calculate the mass per cent of calcium, phosphorus and oxygen in calcium phosphate $C{{a}_{3}}{{(P{{O}_{4}})}_{2}}.$

Molecule = $C{{a}_{3}}{{\left( P{{O}_{4}} \right)}_{2}}$ Mass of =$Ca=3\times 40=120amu$ Mass of Phosphorous = $2\times 31=62amu$ Mass of Oxygen = $8\times 16=128amu$ $\therefore$Molar mass of $C{{a}_{3}}{{(P{{O}_{4}})}_{2}}=120+62+128=310amu$ Mass % of Calcium = $\frac{120}{310}\times 100=38.7%$ Mass % of Phosphorous = $\frac{62}{310}\times 100=20%$ Mass % of Oxygen = $\frac{128}{310}\times 100=41.3%$