posted by Tasha .
A 28 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 19.5 g. What
was the mass of iron in the sample of ore?
Answer in units of g.
2Fe(ore) + ???? ==> Fe2O3 + other stuff.
mass Fe2O3 = 19.5. Convert to moles Fe2O3.
19.5/160 = 0.122 moles.
moles Fe is 0.122 x 2 (there are two moles Fe for every 1 mole Fe2O3) = 0.244 moles Fe.
g Fe = moles x molar mass.
I estimated the molar mass of Fe2O3. You should back track and do that more more exacting than I.