Giả sử :
\(n_{MgO}=a\left(mol\right),n_{Fe_2O_3}=b\left(mol\right)\)
\(\Rightarrow m_{hh}=40a+160b=28\left(g\right)\left(1\right)\)
\(n_{HCl}=\dfrac{200\cdot21.9\%}{36.5}=1.2\left(mol\right)\)
\(PTHH:\)
\(MgO+2HCl\rightarrow MgCl_2+H_2O\)
\(Fe_2O_3+6HCl\rightarrow2FeCl_3+3H_2O\)
Từ PTHH :
\(n_{HCl}=2a+6b=1.2\left(mol\right)\left(2\right)\)
\(\left(1\right),\left(2\right):a=0.3,b=0.1\)
\(\%m_{MgO}=\dfrac{0.3\cdot40}{28}\cdot100\%=42.85\%\)
\(\%m_{Fe_2O_3}=100-42.85=57.15\%\)