The empirical formula corresponds to the simplest form of expressing a compound, it indicates the proportion of atoms in the molecule.
We have two elements S and F and they give us the mass resulting from the decomposition of the molecule. We can find the moles of each element using the atomic weight of each element as follows:
[tex]\begin{gathered} \text{Moles S= Given g of S}\times\frac{1\text{ mol S}}{AtomicWeight,\text{ g S}} \\ \text{Moles S= 0.905 g of S}\times\frac{1\text{ mol S}}{32.065\text{ g S}}=0.028\text{mol S} \end{gathered}[/tex][tex]\begin{gathered} \text{Moles F= Given g of F}\times\frac{1\text{ mol F}}{AtomicWeight,\text{ g F}} \\ \text{Moles F=3.221 g of F}\times\frac{1\text{ mol F}}{18.998\text{g F}}=0.170\text{mol F} \end{gathered}[/tex]
To find the ratio between the elements we divide the moles of each element by the smallest number of moles found, that is by 0.028 moles.
[tex]\begin{gathered} S\rightarrow\frac{0.028}{0.028}=1 \\ F\rightarrow\frac{0.170}{0.028}=6 \end{gathered}[/tex]
Therefore the empirical formula of the compound will be:
[tex]SF_6[/tex]
