Mg+O2--t*->MgO
x____________x
4Al+3O2--t*->2Al2O3
y____________1/2y
Hệ pt:
\(\left\{{}\begin{matrix}24x+27y=15,45\\40x+51y=27,85\end{matrix}\right.\Rightarrow\left\{{}\begin{matrix}x=0,25\\y=0,35\end{matrix}\right.\)
=>mMg=0,25.24=6(g)
=>%mMg=6/15,45.100%~39%
=>%mAl=100%-39%=61%