cân bằng phương trình bằng cách oxi hóa khử FeS2 + O2 —> Fe2O3 + SO2 FeS + KNO3 —> KNO2 + Fe2O3 + SO3 FeS2 + HNO3 —-> Fe(NO3)3 + H2SO4 + NO2

`a,`

\(\rm \mathop{FeS_2}\limits^{0}\to \mathop{Fe}\limits^{+3}+2\mathop{S}\limits^{+4}+11e\hspace{1,2cm}|\times4 \\\mathop{O_2}\limits^{+0}+4e\to 2\mathop{O}\limits^{-2}\hspace{3cm}|\times11\)

$\to 4FeS_2+11O_2\xrightarrow{t^o}2Fe_2O_3+8SO_2$

`b,`

\(\rm \mathop{FeS}\limits^{0}\to \mathop{Fe}\limits^{+3}+\mathop{S}\limits^{+6}+9e\hspace{1,5cm}|\times2\\\mathop{N}\limits^{-5}+2e\to \mathop{N}\limits^{-3}\hspace{3cm}|\times9\)

`2FeS+9KNO_2->Fe_2O_3+9KNO_2+2SO_4`

`c,`

\(\rm \mathop{FeS_2}\limits^{0}\to1\mathop{Fe}\limits^{+3}+2\mathop{S}\limits^{+6}+15e\hspace{0,9cm}|\times4 \\\mathop{N}\limits^{+5}+e\to \mathop{N}\limits^{+4}\hspace{3,5cm}|\times15\)

`->FeS_2+18HNO_3->Fe(NO_3)_3+15NO_2+2H_2SO_4+7H_2O`