PTHH: \(Mg+2HCl\rightarrow MgCl_2+H_2\uparrow\)
\(Al_2O_3+6HCl\rightarrow2AlCl_3+3H_2O\)
Ta có: \(\left\{{}\begin{matrix}\Sigma n_{HCl}=0,4\cdot2=0,8\left(mol\right)\\n_{H_2}=\dfrac{2,24}{22,4}=0,1\left(mol\right)\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}n_{Mg}=0,1mol\\n_{Al_2O_3}=0,1mol\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}m_{Al_2O_3}=0,1\cdot102=10,2\left(g\right)\\m_{Mg}=0,1\cdot24=2,4\left(g\right)\end{matrix}\right.\)
\(\Rightarrow m_{hh}=10,2+2,4=12,6\left(g\right)\)
Theo PTHH: \(\left\{{}\begin{matrix}n_{MgCl_2}=n_{Mg}=0,1mol\\n_{AlCl_3}=2n_{Al_2O_3}=0,2mol\end{matrix}\right.\) \(\Rightarrow\left\{{}\begin{matrix}m_{MgCl_2}=0,1\cdot95=9,5\left(g\right)\\m_{AlCl_3}=0,2\cdot133,5=26,7\left(g\right)\end{matrix}\right.\)
Mặt khác: \(\left\{{}\begin{matrix}m_{ddHCl}=400\cdot1,2=480\left(g\right)\\m_{H_2}=0,1\cdot2=0,2\left(g\right)\end{matrix}\right.\)
\(\Rightarrow m_{dd}=m_{hh}+m_{ddHCl}-m_{H_2}=492,4\left(g\right)\)
\(\Rightarrow\left\{{}\begin{matrix}C\%_{MgCl_2}=\dfrac{9,5}{492,4}\cdot100\%\approx1,93\%\\C\%_{AlCl_3}=\dfrac{26,7}{492,4}\cdot100\%\approx5,42\%\end{matrix}\right.\)