Quy đổi thành Fe (a mol), O (b mol)
\(H_2+\left[O\right]->H_2O\\ n_O=n_{H_2}=0,05mol\\ m_{O\left(hh\right)}=16.0,05=0,8g\\ n_{Fe\left(hh\right)}=\dfrac{3,04-0,8}{56}=0,04mol\\ BT.electron:2n_{SO_2}+2n_O=3n_{Fe}\\ n_{SO_2}=\dfrac{3.0,04-2.0,05}{2}=0,01mol\\ V=22,4.0,01=2,24L\)