Gọi: CT của oxit : MO
MO + H2SO4 --> MSO4 + H2O
M+16___________M+96
8________________24
<=> 8*(M+96) = 24*(M+16)
=> M = 24 (Mg)
CT : MgO
nMgO = 8/40=0.2 mol
nMgSO4 = 0.2 mol
mNaOH = 12g
nNaOH = 0.3 mol
2NaOH + MgSO4 --> Na2SO4 + Mg(OH)2
Bđ: 0.3_______0.2
Pư : 0.3_______0.15________________0.15
Kt: 0 _________0.05________________0.15
mMg(OH)2= 0.15*58=8.7g