# How do I find the percentage composition of Nitrogen in N_2O5?

## How do I find the percentage composition of Nitrogen in ${N}_{2} {O}_{5}$ ?

Mar 8, 2016

You need to take the ratio of the mass of nitrogen to the mass of the entire molecule.

#### Explanation:

This is actually fairly straight-forward.

You know that ${N}_{2} {O}_{5}$ has two nitrogen atoms and five oxygen atoms.

You also know how much a mole of ${N}_{2} {O}_{5}$ masses (2 x 14.007 + 5 x 15.9994), or 108.011 grams per mole.

So the question really is, what % of the mass of a mole of ${N}_{2} {O}_{5}$ is nitrogen?

That would be the total mass of nitrogen, 2 x 14.007 divided by 108.011, and multiplied by 100%.

If you've done everything correctly, you should get: 25.936247234%.

Adjusting to 5 significant figures: 25.936%