\(n_{KMnO_4\left(bđ\right)}=\dfrac{221,8}{158}=\dfrac{1109}{790}\left(mol\right)\Rightarrow n_{KMnO_4\left(pư\right)}=\dfrac{1109}{790}.90\%\approx1,263\left(mol\right)\)
PTHH: \(2KMnO_4\underrightarrow{t^o}K_2MnO_4+MnO_2+O_2\)
1,263------------------------->0,6315
=> \(V_{O_2}=0,6315.22,4=14,1456\left(l\right)\)