Find the empirical formula for an ore that analyzes for 11.89 g of Fe for 16.99 g of of the ore, FexOy

Question

I pretty much understand this problem, I'm just having trouble getting the mole ratio. Can someone please do this problem for me with showing all the work so I can understand please? Thank you! I need this done as soon as possible!!!! By the way, the "x" and 'y" in FexOy are place holders for the subscripts.

Answer 1

Find the moles of Fe and the moles of O:

The question isn't written properly so I'm guessing that it means 11.89 g of Fe out of a total mass of 16.99 g of ore. That means we have to find the mass of oxygen before proceeding.

moles Fe = 11.89 g Fe x 1 mole Fe/55.85 g = 0.2129 moles Fe

mass of O = 16.99 g - 11.89 g = 5.1 g O x 1 mol O/15.99 g = 0.3189 moles O

Divide by the lowest value (0.2129) to get

1 mole Fe

1.5 moles O

Next multiply both by 2 to get whole numbers and we find...

2 moles Fe

3 moles O

Empirical formula for the ore = Fe2O3