MgSO4 --> MgO-->MgCL2-->Mg(OH)2--->MgSo4
MgSO4+H2O=H2SO4+MgO
MgO+CuCI2=MgCI2+CuO
MgCI2+2NaOH=Mg(OH)2+2NaCI
Mg(OH)2+K2SO4=MgSO4+2KOH