[freelancer799]

0.6215 g of an iron-containing compound yielded 0.1303 g of Fe₂O₃ upon oxidation. what is the mass percent of iron in the compound?

[DevaDevil]

attempt?

[freelancer799]

yeah i tried to just take the normal mass percent of Fe₂O₃ but all i got was 69.94 percent and that apparently is not correct so I'm a little lost where to go after getting the molar mass of the substance

[DevaDevil]

the trick is to assume the original compound's iron content is completely oxidised.

That means that from the mass of iron oxide formed you can get the number of moles of iron, and thus the mass of iron present in the original compound. This will lead to the mass% iron: mass iron/total mass compound * 100%

my answer would be 14.66 mass% iron, see if you get that from your calculation as well