PTHH ( I ) : \(Mg+2HCl\rightarrow MgCl_2+H_2\)
.....................x...........2x...............x............x........
PTHH ( II ) : \(Zn+2HCl\rightarrow ZnCl_2+H_2\)
.......................y.........2y..............y..............y............
- Gọi số mol của Mg, Zn có trong hỗn hợp lần lượt là x, y ( x, y > 0 )
Ta có : \(m_{hh}=m_{Zn}+m_{Mg}=n_{Zn}.M_{Zn}+n_{Mg}.M_{Mg}=15,4\)
=> \(m_{hh}=24x+65y=15,4\left(I\right)\)
\(n_{H_2}=\frac{V_{H_2}}{22,4}=\frac{6,72}{22,4}=0,3\left(mol\right)\)
Mà \(n_{H_2}=n_{H_2\left(I\right)}+n_{H_2\left(II\right)}\)
=> \(x+y=0,3\left(II\right)\)
- Từ ( I ) và ( II ) ta có hệ phương trình : \(\left\{{}\begin{matrix}24x+65y=15,4\\x+y=0,3\end{matrix}\right.\)
=> \(\left\{{}\begin{matrix}24\left(0,3-y\right)+65y=15,4\\x=0,3-y\end{matrix}\right.\)
=> \(\left\{{}\begin{matrix}41y=8,2\\x=0,3-y\end{matrix}\right.\)
=> \(\left\{{}\begin{matrix}y=0,2\\x=0,3-0,2=0,1\end{matrix}\right.\) ( TM )
-> \(\left\{{}\begin{matrix}n_{Mg}=0,1\left(mol\right)\\n_{Zn}=0,2\left(mol\right)\end{matrix}\right.\)
=> \(m_{ZnCl_2}=n_{ZnCl_2}.M_{ZnCl_2}=0,2.\left(56+35,5.2\right)=25,4\left(g\right)\)
=> \(m_{MgCl_2}=n_{MgCl_2}.M_{MgCl_2}=0,1.\left(24+35,5.2\right)=9,5\left(g\right)\)
