Question

A sample of a compound was analyzed and found to contain 52.35 % iron, 13.82 % sulfur, and 33.83 % oxygen by mass. Determine the empirical formula of the compound.

Answer 1

To determine the empirical formula of the compound, we need to convert the mass percentages to moles and then find the mole ratio of each element.1. Convert mass percentages to grams  assuming we have a 100 g sample :- Iron  Fe : 52.35 g- Sulfur  S : 13.82 g- Oxygen  O : 33.83 g2. Convert grams to moles using the molar mass of each element:- Molar mass of Fe = 55.85 g/mol- Molar mass of S = 32.07 g/mol- Molar mass of O = 16.00 g/mol- Moles of Fe = 52.35 g / 55.85 g/mol = 0.937 mol- Moles of S = 13.82 g / 32.07 g/mol = 0.431 mol- Moles of O = 33.83 g / 16.00 g/mol = 2.114 mol3. Determine the mole ratio by dividing each value by the smallest number of moles:- Fe: 0.937 mol / 0.431 mol = 2.17  2- S: 0.431 mol / 0.431 mol = 1- O: 2.114 mol / 0.431 mol = 4.90  54. The empirical formula is Fe2S1O5 or Fe2SO5.