# What is the chemical formula of iron(Ill) sulfide?

$F {e}_{2} {S}_{3}$; i.e. an analogue of ferric oxide, $F {e}_{2} {O}_{3}$.
Sulfur typically has a $- 2$ oxidation state (it is a Group VI atom, and its redox chemistry follows that of oxygen). And $F {e}^{3 +}$, ferric ion, has a $+ 3$ oxidation state. We cross multiply and get the given formula.