# How many molecules are there in 24 grams of FeF_3?

Jan 11, 2017

$1.2 \times {10}^{23}$ molecules.

#### Explanation:

The SAME number of molecules are in ANY “mole” of a compound or element. So, you only need to multiply the number of moles given by Avogadro's Number to find how many molecules there are.

Moles are calculated from the molecular weight. For $F e {F}_{3}$ this would be

$55.8 + 3 \cdot 19 = \text{116 g/mole}$

${\text{24 g" / "116 g/mol" = "0.207 moles of FeF}}_{3}$

$\text{0.207 moles" xx 6.022 xx 10^23"molecules/mole" = 1.2 xx 10^23"molecules}$

If you want to find the number of atoms in the sample, you can then take the calculated number of molecules and multiply it by the number of elements in the compound.