A 12.8 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 21.3 g.
What was the mass of iron in the sample of
ore?
Answer in units of g
21.3 g Fe2O3 x (1 mol Fe2O3/molar mass Fe2O3) x (2 mol Fe/1 mol Fe2O3) x (atomic mass Fe/1 mol Fe) = g Fe
Note: There is an easier way to do this if you use the chemical factor; however, schools don't teach that anymore.
21.3 x *(2Fe/Fe2O3) = 21.3 x (2*55.85/159.6) = ? g Fe.