# How do I find the percentage composition of Oxygen in N_2O_5?

It is 74.1%

#### Explanation:

First we find the molar mass of the entire molecule. So N is 14 and O is 16. Molar mass of ${N}_{2} {O}_{5} = 2 \left(14\right) + 5 \left(16\right) = 108$ g/mol.

To find of the percent we take the element's mass in the molecule over the total molar mass. For $O$ would be $\left(\frac{5 \cdot 16}{108}\right) \cdot 100$ or 100%-25.9% = 74.1%

Feb 27, 2016

${N}_{2} {O}_{5}$ molecule contains 2 N atoms and 5 O atoms, So the molar mass of ${N}_{2} {O}_{5}$ =2 x atomic mass of N +5xatomic mass of O = 2x14+5x16=108 g/mole
% of N = $2 \cdot \frac{14}{108} \cdot 100$ =25.93
% of O =$5 \cdot \frac{16}{108} \cdot 100$=74.07