Question

Calculate the imperial formula of the compound. Express your answer as a chemical formula.

Answer 1

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:

`\begin{gathered} \text{Moles S= Given g of S}*\frac{1\text{ mol S}}{AtomicWeight,\text{ g S}} \\ \text{Moles S= 0.905 g of S}*\frac{1\text{ mol S}}{32.065\text{ g S}}=0.028\text{mol S} \end{gathered}`
`\begin{gathered} \text{Moles F= Given g of F}*\frac{1\text{ mol F}}{AtomicWeight,\text{ g F}} \\ \text{Moles F=3.221 g of F}*\frac{1\text{ mol F}}{18.998\text{g F}}=0.170\text{mol F} \end{gathered}`

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.

`\begin{gathered} S\rightarrow(0.028)/(0.028)=1 \\ F\rightarrow(0.170)/(0.028)=6 \end{gathered}`

Therefore the empirical formula of the compound will be:

`SF_6`