A sample of black mineral hematite, an oxide of iron found in many iron ores, contains 34.97 g of iron and 15.03 g oxygen. What is the empirical formula for hematite?

Answer 1

To find the empirical formula, we need to determine the moles of each element in the sample.

The molar mass of iron (Fe) is 55.85 g/mol, and the molar mass of oxygen (O) is 16 g/mol.

First, let's find the moles of iron (Fe):
moles of Fe = mass of Fe / molar mass of Fe
moles of Fe = 34.97 g / 55.85 g/mol
moles of Fe = 0.626 mol

Next, let's find the moles of oxygen (O):
moles of O = mass of O / molar mass of O
moles of O = 15.03 g / 16 g/mol
moles of O = 0.939 mol

Now, let's find the mole ratio of Fe to O:
Fe:O = 0.626 mol Fe / 0.939 mol O
Fe:O ≈ 1:1

Therefore, the empirical formula for hematite is FeO.