Đáp án đúng: A
27; 3,36; 2,16.
Phần 1:
$\begin{array}{l}\text{Fe}\xrightarrow{{}}\overset{\text{+2}}{\mathop{\text{Fe}}}\,\text{+2e}\\\text{x}\,\text{mol}\,\,\xrightarrow{{}}\,\,\,\text{2x}\\\text{M}\xrightarrow{{}}\overset{\text{+n}}{\mathop{\text{M}}}\,\text{+ne}\\\text{y}\,\text{mol}\,\,\xrightarrow{{}}\,\,\text{ny}\end{array}$
$\begin{array}{l}\text{2}{{\text{H}}^{\text{+}}}\text{+2e}\xrightarrow{{}}{{\text{H}}_{\text{2}}}\\\,\,\,\,\,\,\,\,\,\text{0,18}\,\,\,\leftarrow \,\,\,\text{0,09}\end{array}$
⇒ 2x + ny = 0,18 và 56x + M.y = 2,76.
Phần 2:
$\begin{array}{l}\text{Fe}\xrightarrow{{}}\overset{\text{+}{}^{\text{8}}\!\!\diagup\!\!{}_{\text{3}}\;}{\mathop{\text{Fe}}}\,\text{+}\frac{\text{8}}{\text{3}}\text{e}\\\text{x}\,\text{mol}\,\,\xrightarrow{{}}\,\,\,\,\frac{8}{\text{3}}\text{x}\\\text{M}\xrightarrow{{}}\overset{\text{+n}}{\mathop{\text{M}}}\,\text{+ne}\\\text{y}\,\text{mol}\,\,\xrightarrow{{}}\,\,\text{ny}\end{array}$
$\begin{array}{l}\Rightarrow \frac{\text{8}}{\text{3}}\text{x}\,\text{+}\,\text{ny}\,\text{=}\,\text{0,2}\Rightarrow x\text{ }=\text{ }0,03\Rightarrow \text{ny =}\,\text{0,12}\Rightarrow \text{y}\,\text{=}\frac{\text{0,12}}{\text{n}}\\\Rightarrow \text{M}\,\text{=}\frac{\text{2,76-0,03}\text{.56}}{\text{0,12}}\text{.n}\,\text{=}\,\text{9n}\Rightarrow \text{Al}\end{array}$
