a) $Fe_3O_4 + 4H_2 \xrightarrow{t^o} 3Fe + 4H_2O$
$n_{Fe_3O_4} = \dfrac{23,2}{232} = 0,1(mol)$
$n_{H_2} = 4n_{Fe_3O_4} = 0,4(mol)$
$V_{H_2} = 0,4.22,4 = 8,96(lít)$
b) $n_{Fe} = 3n_{Fe_3O_4} = 0,3(mol)$
$m_{Fe} = 0,3.56 = 16,8(gam)$
Fe3O4+4H2-to>3Fe+4H2O
0,1--------0,4-----0,3
n Fe3O4=\(\dfrac{23,2}{232}\)=0,1 mol
=>VH2=0,4.22,4=8,96l
=>m Fe=0,3.56=16,8g