# A sample of an iron sulfide contains 2.561*g of metal, and 2.206*g of sulfur. What is the empirical formula of iron sulfide?

Jun 10, 2016

$F {e}_{2} {S}_{3}$

#### Explanation:

$\text{Moles of iron}$ $=$ $\frac{2.561 \cdot g}{55.85 \cdot g \cdot m o {l}^{-} 1}$ $=$ $0.0459 \cdot m o l$

$\text{Moles of sulfur}$ $=$ $\frac{2.206 \cdot g}{32.06 \cdot g \cdot m o {l}^{-} 1}$ $=$ $0.0688 \cdot m o l$

If we divide thru by the lower molar quantity, we get, $F e {S}_{1.5}$. However, by definition, the empirical formula is the simplest WHOLE number that defines constituent elements in a species, so we double the formula to get WHOLE numbers:

$F {e}_{2} {S}_{3}$.