a. Đặt \(\left\{{}\begin{matrix}n_{Fe}=x\left(mol\right)\\n_{Al}=y\left(mol\right)\end{matrix}\right.\)
\(n_{H_2}=\dfrac{5,6}{22,4}=0,25\left(mol\right)\\ PTHH:Fe+2HCl\rightarrow FeCl_2+H_2\\ 2Al+6HCl\rightarrow2AlCl_3+3H_2\\ \Rightarrow\left\{{}\begin{matrix}56x+27y=8,3\\x+1,5y=0,25\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=0,1\left(mol\right)\\y=0,1\left(mol\right)\end{matrix}\right.\\ \Rightarrow\%m_{Fe}=\dfrac{0,1\cdot56}{8,3}\cdot100\%\approx67,4\%\\ \Rightarrow\%m_{Al}\approx32,6\%\)
b. \(n_{HCl}=2n_{Fe}+3n_{Al}=0,2+0,3=0,5\left(mol\right)\)
\(\Rightarrow V_{dd_{HCl}}=\dfrac{0,5}{2}=0,25\left(l\right)\)
