# What is the percent composition of Na_3PO_4?

Feb 19, 2016

42.1% Na, 18.9%P, 39%O

#### Explanation:

The molar mass of sodium phosphate is ${M}_{r} = \left(3 \times 23\right) + 31 + \left(4 \times 16\right) = 164 g / m o l$.

Now consider 1 mole of $N {a}_{3} P {O}_{4}$ which has a mass of $164 g$:

$3 \times 23 = 69 g$ is sodium, $31 g$ is phosphorous, $4 \times 16 = 64 g$ is oxygen.

Therefore the percentage composition of each element is:

69/164xx100=42.1% Na

31/164xx100=18.9% P

64/164xx100=39% O