a) Chất rắn sau pư là Cu
=>m\(_{Zn}+m_{Fe}=20-1,4=18,6\left(g\right)\)
Zn+2HCl--->ZnCl2+H2
x-------2x-----------------x
Fe+2HCl------>FeCl2+H2
y---------2y-------------y
Ta có
nH2 =0,3(mol)
n\(_{HCl}=\frac{200.18,25}{100.36,5}=1\left(mol\right)\)
Theo pthh
n\(_{HCl}=2n_{H2}=0,6\left(mol\right)\)
=> n HCl dư
Theo bài ta có hệ pt
\(\left\{{}\begin{matrix}65x+56y=18,6\\x+y=0,3\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=0,2\\y=0,1\end{matrix}\right.\)
%m\(_{Cu}=\frac{1,4}{20}.100\%=7\%\)
%m\(_{Zn}=\frac{0,2.65}{20}.100\%=65\%\)
%m Fe=100-7-65=28%
b) Tự lm nhé
