I need help with a question!
a)What mass of iron may be extracted from 1000 tonnes of Fe3O4 according to
3Fe3O4(s)+8Al(s)-->4Al2O3(s)+9Fe(s)?
b) What mass of aluminium is used in the process?
All help would be appreciated. Thanks!
a) 1000 t = 1000 kg = 1000000 g
n(Fe3O4) = 1000000 g / 231.533 g/mol = 4319.0387547... mol
n(Fe) = 3 x n(Fe3O4)
m(Fe) = (3 x 4319.0387547... mol) x 55.845 g/mol x 1/1000 kg/g = 723.6 kg to 4 sig figs
b) n(Al) = (8/3) x n(Fe3O4)
m(Al) = (8/3) x 4319.0387547... mol x 26.98 g/mol x 1/1000 kg/g = 310.7 kg to 4 sig figs
Note that you can check if your calculations are correct or not with dimensional analysis, all units will cancel to the appropriate unit of the final answer if you did everything correctly. For example, mol cancels out mol
-1 or /mol and g cancels out g
-1 or /g etc