# How many moles are in a sample of CO_2 that contains 8.12*10^22 of O atoms?

Feb 3, 2016

0.067mols

#### Explanation:

$C {O}_{2}$

From the formula we can see that,

$2 \times 6.02 \times {10}^{23}$atoms of $O$ are in $6.02 \times {10}^{23}$ molecules of $C {O}_{2}$
$\therefore 1$ atom of $O$ is in $\frac{6.02 \times {10}^{23}}{2 \times 6.02 \times {10}^{23}}$ molecules of $C {O}_{2}$
$\therefore 8.12 \times {10}^{22}$ atoms of $O$ are in $\frac{6.02 \times {10}^{23} \times 8.12 \times {10}^{22}}{2 \times 6.02 \times {10}^{23}}$ molecules of $C {O}_{2}$

$= 4.06 \times {10}^{22}$ molecules

we know,

$n = \frac{N}{N} _ A$

$= \frac{4.06 \times {10}^{22}}{6.02 \times {10}^{23}}$

$= 0.067 m o l s$