Quá trình:
\(Fe_x^{^{+\dfrac{2y}{x}}}\rightarrow xFe^{+3}+\left(3x-2y\right)|\times4\)
\(N^{+5}+3e\rightarrow N^{+2}|\times\left(3x-2y\right)\)
\(N^{+5}+1e\rightarrow N^{+4}|\times\left(3x-2y\right)\)
PT: \(4Fe_xO_y+\left(18x-4y\right)HNO_3\rightarrow4xFe\left(NO_3\right)_3+\left(3x-2y\right)NO+\left(3x-2y\right)NO_2+\left(9x-2y\right)H_2O\)