Hòa tan hoàn toàn 18,94 gam hỗn hợp X gồm Al, Zn, MgO, Cu(NO3)2

* Hướng dẫn giải

Chọn đáp án C

$\begin{array}{l} \left\{\begin{array}{l}{\overline{M}}_{Kh́i}=10,482\\ 1 kh́i hòua na^au\end{array}\right.\Rightarrow khí là \left\{\begin{array}{l}NO\\ H_2\end{array}\right.\Rightarrow \left\{\begin{array}{l}{n}_{NO}+n_{H_2}=0,19\\ 30n_{NO}+2n_{H_2}=0,19.10,842\end{array}\right.\Rightarrow \left\{\begin{array}{l}{n}_{NO}=0,06\\ n_{H_2}=0,13\end{array}\right.\\ + BTKL\Rightarrow n_{H_{2}O}=\frac{18,94+0,43.98-0,19.10,842-54,34}{18}=0,26\Rightarrow n_{N{H_4}^{+}}=\frac{0,43.2-0,13.2-0,26.2}{4}=0,02\end{array}$

$\begin{array}{l}\Rightarrow n_{Cu{\left(N{O}_3\right)}_2}=\frac{0,06+0,02}{2}=0,04.\\ + n_{H^{+}}=2n_{H_2}+4n_{NO}+10n_{N{H_4}^{+}}+2n_{O^{2-}}\Rightarrow n_{O^{2-}}=\frac{0,43.2-2.0,13-0,06.4-0,02.10}{2}=0,08\Rightarrow n_{MgO}=0,08.\\ + \left\{\begin{array}{l}27n_{Al}+65n_{Zn}=18,94-0,04.188-0,08.40\\ 3n_{Al}+2n_{Zn}=0,06.3+0,02.8+0,13.2\end{array}\right.\Rightarrow \left\{\begin{array}{l}x=0,16\\ y=0,06\end{array}\right.\Rightarrow \%Al=22,8\%\end{array}$