Em tham khảo nha:
\(\begin{array}{l}
9)\\
4Fe{(Cr{O_2})_2} + 8N{a_2}C{O_3} + 7{O_2} \to 8N{a_2}Cr{O_4} + 2F{e_2}{O_3} + 8C{O_2}\\
4 \times |Fe{(Cr{O_2})_2} \to F{e^{ + 3}} + 4{O^{ - 2}} + 2C{r^{ + 6}} + 7e\\
7 \times |{O_2} + 4e \to 2{O^{ - 2}}\\
10)\\
2KN{O_3} + S + 3C \to {K_2}S + {N_2} + 3C{O_2}\\
3 \times |C \to {C^{ + 4}} + 4e\\
1 \times |2{N^{ + 5}} + 10e \to {N_2}\\
1 \times |S + 2e \to {S^{ - 2}}\\
11)\\
4FeC{u_2}{S_2} + 15{O_2} \to 2F{e_2}{O_3} + 8CuO + 8S{O_2}\\
4 \times |FeC{u_2}{S_2} \to F{e^{ + 3}} + 2C{u^{2 + }} + 2{S^{ + 4}} + 15e\\
15 \times |{O_2} + 4e \to 2{O^{ - 2}}
\end{array}\)
