Question

A compound is found to contain 53.70% iron and 46.30% sulfur. What is its empirical formula?

Answer 1

`Fe_2S_3`

Explanation:

In 100 g of the compound, there are 53.7 g iron, and 46.3 g of sulfur.

We divide thru by the ATOMIC masses of each constituent:

`Fe:` `(53.7*cancelg)/(55.85*cancelg*mol^-1)` `=` `0.961` `mol`.

`S:` `(46.3*cancelg)/(32.06*cancelg*mol^-1)` `=` `1.44` `mol`.

Now we divide thru by the LOWEST molar quantity to give...

`Fe:S` `=` `1:1.50`.

Now, the empirical formula is, by definition, the simplest `"WHOLE number ratio"` that defines constituent atoms in a species. To get whole numbers, clearly we have to multiply the given ratio by 2, to give (FINALLY):

`Fe_2S_3`