Question 2df5d

Aug 18, 2017

There are no nitrogen molecules in your sample.

Explanation:

As its chemical formula suggests, a molecule of dinitrogen pentoxide, ${\text{N"_2"O}}_{5}$, contains

• two atoms of nitrogen, $2 \times \text{N}$
• five atoms of oxygen, $5 \times \text{O}$

These atoms are covalently bonded to form a molecule of dinitrogen pentoxide, so you can't really talk about nitrogen molecules here.

However, you can calculate the number of atoms of nitrogen present in the sample.

To do that, use the fact that in order to have $1$ mole of dinitrogen pentoxide, you need to have $6.022 \cdot {10}^{23}$ molecules of dinitrogen pentoxide $\to$ think Avogadro's constant here.

This implies that your sample contains

0.23 color(red)(cancel(color(black)("moles N"_2"O"_5))) * (6.022 * 10^(23)color(white)(.)"molecules N"_ 2"O"_ 5)/(1color(red)(cancel(color(black)("mole N"_2"O"_5))))

$= 1.385 \cdot {10}^{23} \textcolor{w h i t e}{.} {\text{molecules N"_2"O}}_{5}$

Now, you know that each molecule of dinitrogen pentoxide contains $2$ atoms of nitrogen, so you can say that your sample contains

1.385 * 10^(23)color(red)(cancel(color(black)("molecules N"_2"O"_5))) * "2 atoms N"/(1color(red)(cancel(color(black)("molecule N"_2"O"_5))))#

$= \textcolor{\mathrm{da} r k g r e e n}{\underline{\textcolor{b l a c k}{2.8 \cdot {10}^{23} \textcolor{w h i t e}{.} \text{atoms of N}}}}$

The answer is rounded to two sig figs.