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Đáp án+Giải thích các bước giải:

Đáp án+Giải thích các bước giải:

 19) `Fe_3O_4 + HNO_3 -> Fe(NO_3)_3 + NO_2 + H_2O`

\begin{align*}\left.\begin{aligned}1×\\1×\end{aligned}\right|&\left.\begin{aligned}N^{+5}+1e\rightarrow N^{+4}\\3Fe^{+\frac{8}{3}} \rightarrow 3Fe^{+3}+1e\end{aligned}\right.\\\end{align*} 

`Fe_3O_4 + 10HNO_3 -> 3Fe(NO_3)_3 + NO_2 + 5H_2O`

20) `CuO + 2HNO_3 -> Cu(NO_3)_2 + H_2O`

21) `ZnO + 2HNO_3 -> Zn(NO_3)_2 + H_2O`

22) `Fe_xO_y + HNO_{3\ l} -> Fe(NO_3)_3 + NO + H_2O`

\begin{align*}\left.\begin{aligned}(3x-2y)×\\3×\end{aligned}\right|&\left.\begin{aligned}N^{+5}+3e\rightarrow N^{+2}\\xFe^{+\frac{2y}{x}} \rightarrow xFe^{+3}+(3x-2y)e\end{aligned}\right.\\\end{align*} 

`3Fe_xO_y + (12x-2y)HNO_3 -> 3xFe(NO_3)_3 + (3x-2y)NO + (6x-y)H_2O`

23) `Fe_xO_y + HNO_{3\ đ} -> Fe(NO_3)_3 + NO_2 + H_2O`

\begin{align*}\left.\begin{aligned}(3x-2y)×\\1×\end{aligned}\right|&\left.\begin{aligned}N^{+5}+1e\rightarrow N^{+4}\\xFe^{+\frac{2y}{x}} \rightarrow xFe^{+3}+(3x-2y)e\end{aligned}\right.\\\end{align*} 

`Fe_xO_y + (6x-2y)HNO_3 -> xFe(NO_3)_3 + (3x-2y)NO + (3x-y)H_2O`

24) `M_xO_y + HNO_{3\ đ} -> M(NO_3)_n + NO_2 + H_2O`

\begin{align*}\left.\begin{aligned}(nx-2y)×\\1×\end{aligned}\right|&\left.\begin{aligned}N^{+5}+1e\rightarrow N^{+4}\\xM^{+\frac{2y}{x}} \rightarrow xM^{+n}+(nx-2y))e\end{aligned}\right.\\\end{align*} 

`M_xO_y + (2nx-2y)HNO_3 -> xM(NO_3)_n + (nx-2y)NO_2 + (nx-y) H_2O`