posted by Rafael .
A 7.6 g sample of iron ore is treated as follows.
The iron in the sample is all converted by a
series of chemical reactions to Fe2O3. The
mass of Fe2O3 is measured to be 12.9 g. What
was the mass of iron in the sample of ore?
Answer in units of g
Didn't I do this for you (or one similar to it) a couple of days ago.
12.9g x (1 mol Fe2O3/molar mass Fe2O3) x (2 mols Fe/1 mol Fe2O3) x (atomic mass Fe/1 mol Fe) = ?
There is an easier way to do this but chemical factors are not taught in most schools now.
12.9 x (2*Fe/Fe2O3) = 12.9*2*55.85/159.7 = 9.02 g.
Check your post. There is a problem because the mass of Fe CAN'T be more than the 7.6g you started with.