a, Ta có: 24nMg + 27nAl = 12,9 (1)
PT: \(Mg+2HCl\rightarrow MgCl_2+H_2\)
\(2Al+6HCl\rightarrow2AlCl_3+3H_2\)
Theo PT: \(\left\{{}\begin{matrix}n_{MgCl_2}=n_{Mg}\\n_{AlCl_3}=n_{Al}\end{matrix}\right.\) ⇒ 95nMg + 133,5nAl = 59,05 (2)
Từ (1) và (2) \(\Rightarrow\left\{{}\begin{matrix}n_{Mg}=0,2\left(mol\right)\\n_{Al}=0,3\left(mol\right)\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}\%m_{Mg}=\dfrac{0,2.24}{12,9}.100\%\approx37,21\%\\\%m_{Al}\approx62,79\%\end{matrix}\right.\)
b, Theo PT: \(n_{HCl}=2n_{Mg}+3n_{Al}=1,3\left(mol\right)\)
\(\Rightarrow m_{ddHCl}=\dfrac{1,3.36,5}{14,6\%}=325\left(g\right)\)
c, Theo PT: \(n_{H_2}=\dfrac{1}{2}n_{HCl}=0,65\left(mol\right)\)
Ta có: m dd sau pư = 12,9 + 325 - 0,65.2 = 336,6 (g)
\(\Rightarrow\left\{{}\begin{matrix}C\%_{MgCl_2}=\dfrac{0,2.95}{336,6}.100\%\approx5,6\%\\C\%_{AlCl_3}=\dfrac{0,3.133,5}{336,6}.100\%\approx11,9\%\end{matrix}\right.\)