Chemistry Question for daughter?

  • Thread starter Thread starter Analeigh N
  • Start date Start date
A

Analeigh N

Guest
An ore contains Fe3O4 and no other iron. The iron in a 53-gram sample of the ore is all converted by a series of chemical reactions to
Fe2O3. The mass of Fe2O3 is measured to be 14.8 g. What was the mass of Fe3O4 in the sample of ore? Answer in units of grams.
 
here's the steps...

1) convert 14.8 g of Fe2O3 to g Fe
2) convert g Fe to moles Fe
3) convert moles Fe to moles Fe3O4
4) convert moles Fe3O4 to mass Fe3O4

solution...

*** 1 ***
mass ratio of iron to Fe2O3 = (2x55.85) / (2x55.85+3x16.00) = 112 g Fe / 160 g Fe2O3

you follow that?

then...
14.8 g Fe2O3 x (112 g Fe / 160 g Fe2O3) = 10.36 g Fe

*** 2 ***
moles Fe = 10.36 g Fe x (1 mole / 55.85g) = 0.185 moles Fe

*** 3 ***
since... 1 molecule Fe3O4 contains 3 molecules Fe

then....1 mole Fe3O4 contains 3 moles Fe

and therefore...
0.185 moles Fe x (1 mole Fe3O4 / 3 moles Fe) = 0.0618 moles Fe3O4

*** 4 ***
0.0618 moles Fe3O4 x (231.6 g Fe3O4 / mole Fe3O4) = 14.3 g Fe3O4

**************
and if you're wondering... the ore would then be 14.3 / 53 x 100% = 27% Fe3O4

*************
questions about any of this?
 
Back
Top