Ta có nO2 = \(\dfrac{6,72}{22,4}\) = 0,3 ( mol )
3Fe + 2O2 \(\rightarrow\) Fe3O4
x........\(\dfrac{2}{3}\)x..........x/3
Cu + \(\dfrac{1}{2}\)O2 \(\rightarrow\) CuO
y.........y/2..........y
=> \(\left\{{}\begin{matrix}56x+64y=12\\x\dfrac{2}{3}+\dfrac{y}{2}=0,3\end{matrix}\right.\)
=> \(\left\{{}\begin{matrix}x=0,9\\y=-0,6\end{matrix}\right.\)
Hình như đề sai bạn ơi