\(3Fe+2O2-->Fe3O4\)
\(n_{Fe}=\frac{16,8}{56}=0,3\left(mol\right)\)
\(n_{O2}=\frac{11,2}{22,4}=0,5\left(mol\right)\)
\(\frac{0,3}{3}< \frac{0,5}{2}\Rightarrow O2dư\)
Sau phản ứng gồm O2 dư và Fe3O4
\(n_{O2}=\frac{2}{3}n_{Fe}=0,2\left(mol\right)\)
\(n_{O2}dư=0,5-0,2=0,3\left(mol\right)\)
\(\Rightarrow m_{O2}dư=0,3.32=9,6\left(g\right)\)
\(n_{Fe3O4}=\frac{1}{3}n_{Fe}=0,1\left(mol\right)\)
\(m_{Fe3O4}=0,1.232=23,2\left(g\right)\)