a)
$n_{H_2SO_4} = \dfrac{147.20\%}{98} = 0,3(mol)$
$M_2O_n + nH_2SO_4 \to M_2(SO_4)_n + nH_2O$
$n_{oxit} = \dfrac{1}{n}.n_{H_2SO_4} = \dfrac{0,3}{n}(mol)$
$\Rightarrow \dfrac{0,3}{n}.(2M + 16n) = 16 \Rightarrow M = \dfrac{56}{3}n$
Với n = 3 thì M = 56(Fe)
b)
$n_{Fe_2(SO_4)_3} = n_{Fe_2O_3} = \dfrac{16}{160} = 0,1(mol)$
$m_{dd} = 16 + 147 = 164(gam)$
$C\%_{Fe_2(SO_4)_3} = \dfrac{0,1.400}{164} = 24,54\%$
