# Question #d0338

Mar 14, 2017

#### Explanation:

To figure out how many atoms there are, we want to convert to moles. We can easily convert to moles using the molar mass and the mass of the sample. However we don't know what the mass is, we just know the volume. Luckily, they gave us the density which we can use to convert from volume to mass as follows

$550.0 m L \cdot 1.59 \frac{g}{m L} = 874.5 g$

The milliliter units cancel and leave us with an answer whose units are grams. We can use the calculated mass and the molar mass of carbon tetrafluoride which can be looked up to be $153.81 \frac{g}{m o l}$ or you can calculate it by looking at the periodic table and adding the mass of carbon with four times the mass of Cl which would look like

$12.01 g + 4 \left(35.45 g\right) = 153.81 g$

and use that to solve for moles of carbon tetrachloride as follows

$874.5 \frac{g}{153.81 \left(\frac{g}{m o l}\right)} = 5.686 m o l$

Using Avagadro's Number which is $6.022 \cdot {10}^{23} \frac{a}{m o l}$
Where "a" represents atoms we can solve for the number of atoms to be

$5.686 m o l \cdot 6.022 \cdot {10}^{23} \left(\frac{a}{m o l}\right) = 3.42 \cdot {10}^{24} a$