Ncert Exercises & Solutions

Calculate the mass per cent of calcium, phosphorus and oxygen in calcium phosphate ${Ca}_{3} {({PO}_{4})}_{2} .$

Mass per cent of calcium = \frac{3 \times (atomic mass of calcium)}{molecular mass of {Ca}_{3} {({PO}_{4})}_{2}} \times 100

= \frac{120 u}{310 u} \times 100 = 38.71 %

Mass per cent of phosphorus = \frac{2 \times (atomic mass of phosphorus)}{molecular mass of {Ca}_{3} {({PO}_{4})}_{2}} \times 100

= \frac{2 \times 31 u}{310 u} \times 100 = 20 %

Mass per cent of oxygen = \frac{8 \times (atomic mass of oxygen)}{molecular mass of {Ca}_{3} {({PO}_{4})}_{2}} \times 100

= \frac{8 \times 16 u}{310 u} \times 41.29 %