a, Gọi \(\left\{{}\begin{matrix}n_{Mg}:a\left(mol\right)\\n_{Al}:b\left(mol\right)\end{matrix}\right.\)
\(Mg+H_2SO_4\rightarrow MgSO_4+H_2\)
a______a______a___________a
\(2Al+3H_2SO_4\rightarrow Al_2\left(SO_4\right)_3+3H_2\)
b_____3/2b_______b/2_________3/2b
\(n_{H2}=\frac{8,96}{22,4}=0,4\left(mol\right)=a+\frac{3}{2}b\)
\(m_{hh}=m_{Mg}+m_{Al}\Leftrightarrow m_{hh}=n_{Mg}.M_{Mg}+n_{Al}.M_{Al}\)
\(\Leftrightarrow7,8=24a+27b\)
Giải hệ PT :
\(\left\{{}\begin{matrix}a+\frac{3}{2}b=0,4\\24a+27b=7,8\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}a=0,1\\b=0,2\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}m_{Mg}=0,1.24=2,4\left(g\right)\\m_{Al}=0,2.27=5,4\left(g\right)\end{matrix}\right.\)
b, \(n_{H2SO4}=a+\frac{3}{2}b=0,1+\frac{3}{2}.0,2=0,4\left(mol\right)\)
\(\Rightarrow n_{H2SO4\left(pu\right)}=0,4-0,4.10\%=0,36\left(mol\right)\)
\(\Rightarrow V_{H2SO4\left(Cd\right)}=\frac{0,36}{2}=0,18\left(l\right)\)