An iron sulfide compound is analyzed, and found to contain 11.26 g iron and 9.70 g sulfur. Determine the molar ratio of sulfur to iron in this compound, and hence its chemical formula.

Explanation:

First we convert the given masses of each element into moles, using their respective molar masses:

Now we divide them in order to calculate the molar ratio of S to Fe:

Meaning that for each 1 Fe mol, there's 1.5 S moles. We can write that as Fe₁S₁.₅

Finally we double those subscripts so that they become the lowest possible integers: Fe₂S₃.