Đốt cháy m gam hỗn hợp Mg, Fe trong oxi một thời gian, thu được...

$\underbrace{\left\{ \begin{aligned}
& Mg \\
& Fe \\
\end{aligned} \right\}}_{m}\xrightarrow[t{}^\circ ]{{{O}_{2}}}\underbrace{\left\{ X \right\}}_{\left( m+5,28 \right)}\xrightarrow{HCl}\underbrace{\left\{ Y \right\}}_{\left( 3m-0,09 \right)}\xrightarrow{AgN{{O}_{3}}}\underbrace{\left\{ \begin{aligned}
& AgCl\downarrow \\
& Ag\downarrow \\
\end{aligned} \right\}}_{\left( 9m+1,83 \right)}$
$\left\{ \begin{aligned}
& BTKL:{{n}_{{{O}^{2-}}}}=\dfrac{5,28}{16}=0,33 \\
& BTDT:{{n}_{C{{l}^{-}}}}=2{{n}_{{{O}^{2-}}}}=0,66 \\
\end{aligned} \right.\Rightarrow \underbrace{\left( 3m-0,09 \right)}_{{{m}_{muối}}}-\underbrace{\left( m+5,28 \right)}_{{{m}_{oxit}}}=\underbrace{0,66.35,5}_{{{m}_{C{{l}^{-}}}}}-\underbrace{5,28}_{{{m}_{{{O}^{2-}}}}}$
$\Rightarrow m=11,76$.
${{n}_{AgCl}}={{n}_{C{{l}^{-}}}}=0,66\Rightarrow {{n}_{Ag}}=\dfrac{9.11,76+1,83-0,66.143,5}{108}=0,12$.
$\left\{ \begin{aligned}
& {{m}_{\left( Fe,Mg \right)}}=56{{n}_{Fe}}+24{{n}_{Mg}}=11,76 \\
& BTE:3{{n}_{Fe}}+2{{n}_{Mg}}=2{{n}_{{{O}^{2-}}}}+{{n}_{Ag}}=0,78 \\
\end{aligned} \right.\Rightarrow \left\{ \begin{aligned}
& {{n}_{Fe}}=0,12 \\
& {{n}_{Mg}}=0,21 \\
\end{aligned} \right.$
$\Rightarrow $ Trong X: ${{n}_{Fe}}:{{n}_{Mg}}:{{n}_{O}}=0,12:0,21:0,33=4:7:11$
$\left\{ \begin{aligned}
& {{m}_{oxit/4,83m gam}}=56.4a+24.7a+16.11a=4,83.11,76=56,8 \\
& {{m}_{muối}}=242.4a+148.7a \\
\end{aligned} \right.\Rightarrow \left\{ \begin{aligned}
& a=0,1 \\
& x={{m}_{muối}}=200,4 \\
\end{aligned} \right.$.