# What is the total number of nitrogen atoms in 0.25 mole of NO_2 gas?

Feb 21, 2016

$1$ $\text{mol}$ of atoms contains Avogadro's number of atoms. Avogadro's number $=$ ${N}_{A}$ $=$ $6.022140857 \left(74\right) \times {10}^{23}$.

#### Explanation:

So there are $\frac{1}{4}$ $\times$ ${N}_{A}$ nitrogen atoms in such a molar quantity of nitric oxide, approx. $1.5 \times {10}^{23}$ individual nitrogen atoms. How many OXYGEN atoms in such a quantity?

Here I use ${N}_{A}$ as I would use any other collective number: a dozen, a score, a gross. I am perfectly free to do so, because any physical scientist knows precisely what I mean by a $\text{mole}$.