Em tham khảo nha:

\(\begin{array}{l}
1)\\
FeO + {H_2} \xrightarrow{t^0} Fe + {H_2}O\\
2{H_2} + {O_2} \xrightarrow{t^0}  2{H_2}O\\
6FeO + {O_2} \xrightarrow{t^0}  2F{e_3}{O_4}\\
S{O_2} + {H_2}O \to {H_2}S{O_3}\\
2S{O_2} + {O_2} \xrightarrow{t^0,V_2O_5}  2S{O_3}\\
{P_2}{O_5} + 3{H_2}O \to 2{H_3}P{O_4}\\
2K + 2{H_2}O \to 2KOH + {H_2}\\
4K + {O_2} \xrightarrow{t^0}  2{K_2}O\\
2)\\
F{e_2}{O_3} + 3{H_2} \xrightarrow{t^0}  2Fe + 3{H_2}O\\
CuO + {H_2} \xrightarrow{t^0}  Cu + {H_2}O\\
{n_{Fe}} = \dfrac{{2,8}}{{56}} = 0,05\,mol\\
{n_{F{e_2}{O_3}}} = \dfrac{{0,05}}{2} = 0,025\,mol\\
{m_{F{e_2}{O_3}}} = 0,025 \times 160 = 4g\\
{m_{CuO}} = 8 - 4 = 4g\\
{n_{CuO}} = \dfrac{4}{{80}} = 0,05\,mol\\
{n_{Cu}} = {n_{CuO}} = 0,05\,mol\\
{m_{Cu}} = 0,05 \times 64 = 3,2g
\end{array}\)