1) 2FexOy + (6x-2y)H2SO4 ( đặc nóng) → xFe2(SO4)3 + (3x-2y)SO2 + (6x-2y)H2O
\(\left\{{}\begin{matrix}\times1\\\times\left(3x-2y\right)\end{matrix}\right.\left\{{}\begin{matrix}2xFe^{+\dfrac{2y}{x}}-2\left(3x-2y\right)e\rightarrow2xFe^{+3}\\S^{+6}+2e\rightarrow S^{+4}\end{matrix}\right.\)
2) 10Al + 36HNO3 (loãng) → 10Al(NO3)3 + 3N2 + 18H2O
\(\left\{{}\begin{matrix}\times10\\\times3\end{matrix}\right.\left\{{}\begin{matrix}Al^0-3e\rightarrow Al^{+3}\\2N^{+5}+10e\rightarrow N^0_2\end{matrix}\right.\)