posted by Chandler on .
An ore contains Fe3O4 and no other iron. The iron in a 51-gram sample of the ore is all converted by a series of chemical reactions to Fe2O3. The mass of Fe2O3 is measured to be 21.9 g. What was the mass of Fe3O4 in the
sample of ore?
The simple way is to convert mass Fe2O3 into mass Fe3O4 by using a chemical factor (which is not taught anymore).
mass Fe2O3 x (2*molar mass Fe3O4/3*molar mass Fe2O3) = ??
I got 156.356 grams, but it still says that's wrong.
I wonder how you obtained that? Post your work. I don't have anything close to that.
21.9 x (463.07/479.07)=21.1685
Must have done something wrong the first time. Is that right?
Looks ok to me. Now round off to three s.f.
how is the 51 gram sample integrated into the equation then? or is it not used at all in this case?