Question

Two iron oxide samples are given to you where one is red and the other is black. You perform a chemical analysis and you find that the red sample has a Fe/O mass ratio of 2.327 and the black has a Fe/O mass ratio of 3.491. You suspect the red sample is simple rust or Fe2O3. What is the chemical formula for the black sample?

Answer 1

Answer:

Chemical formula for the black iron oxide sample is FeO

Explanation:

Given:

Mass ratio of black iron oxide sample, Fe/O = 3.491

To determine:

The chemical formula

Calculation:

The mass ratio is Fe:O = 3.491 : 1

Mass of Fe = 3.491 g

Mass of O = 1.000 g

Atomic mass of Fe =55.85 g/mol

Atomic mass of O = 16.00 g/mol

$Moles\ Fe = \frac{3.491g}{55.85g/mol} =0.625\\\\Moles\ O = \frac{1.000g}{16.00g/mol} =0.0625$

Therefore, the molar ratio of Fe:O = 1:1

Hence, chemical formula is FeO