Câu hỏi 13

Ta nhận thấy m_E < m_X => KL chưa phản ứng hết; AgNO₃ và Cu(NO₃)₂ hết

\(\begin{gathered}
22,08(g)X\left\{ \begin{gathered}
Mg:a \hfill \\
Fe:b \hfill \\
\end{gathered} \right\} + \left\{ \begin{gathered}
AgN{O_3}:c \hfill \\
Cu{(N{O_3})_2}:2c \hfill \\
\end{gathered} \right\} \to \left\{ \begin{gathered}
Ran\,Y\left\{ \begin{gathered}
Ag:c \hfill \\
Cu:2c \hfill \\
Fe\,du \hfill \\
\end{gathered} \right\} \hfill \\
dd\,Z\xrightarrow{{ + NaOH\,du}} \downarrow T\xrightarrow{{{t^o}}}21,6(g)E\left\{ \begin{gathered}
MgO:a \hfill \\
F{e_2}{O_3} \hfill \\
\end{gathered} \right. \hfill \\
\end{gathered} \right. \hfill \\
\xrightarrow{{BTe}}{n_{Fe\,pu}} = \frac{{c + 2.2c - 2a}}{2} = 2,5c - a \to {n_{Fe\,du}} = b - (2,5c - a) = a + b - 2,5c \hfill \\
22,08(g)X\left\{ \begin{gathered}
Mg:a \hfill \\
Fe:b \hfill \\
\end{gathered} \right\} + \left\{ \begin{gathered}
AgN{O_3}:c \hfill \\
Cu{(N{O_3})_2}:2c \hfill \\
\end{gathered} \right\} \to \left\{ \begin{gathered}
Ran\,Y\left\{ \begin{gathered}
Ag:c \hfill \\
Cu:2c \hfill \\
Fe\,du:a + b - 2,5c \hfill \\
\end{gathered} \right\} \hfill \\
dd\,Z\xrightarrow{{ + NaOH\,du}} \downarrow T\xrightarrow{{{t^o}}}21,6(g)E\left\{ \begin{gathered}
MgO:a \hfill \\
F{e_2}{O_3}:\frac{{2,5c - a}}{2} \hfill \\
\end{gathered} \right. \hfill \\
\end{gathered} \right. \hfill \\
(1)\xrightarrow{{BTe}}{n_{Ag}} + 2{n_{Cu}} + 3{n_{Fe\,du}} = 2{n_{S{O_2}}} \to c + 2.2c + 3(a + b - 2,5c) = 0,675.2 \hfill \\
(2){m_{Mg}} + {m_{Fe}} = {m_X} \to 24x + 56y = 22,08 \hfill \\
(3){m_E} = {m_{MgO}} + {m_{F{e_2}{O_3}}} \to 40a + 160\left( {\frac{{2,5c - a}}{2}} \right) = 21,6 \hfill \\
\to \left\{ \begin{gathered}
a = 0,36 \hfill \\
b = 0,24 \hfill \\
c = 0,18 \hfill \\
\end{gathered} \right. \to x = \frac{{0,18}}{{0,15}} = 1,2M \hfill \\
\end{gathered} \)

Đáp án B