What is the empirical chemical formula of a compound that is 69.9% of iron and 30.0% oxygen?

1 Answer
Apr 24, 2016

Fe2O3

Explanation:

We assume there are 100g of compound, and thus there are:

(i) 69.9g55.85gmol1 = 1.25molFe, and

(ii) 30.0g15.999gmol1 = 1.88molO.

If we divide thru by the lowest molar quantity we get a formula of FeO1.5. Because, by definition the empirical formula is the simplest WHOLE number ratio, we double this result to give Fe2O3.