Mg(oh)2->mgo->mgcl2->mg(oh)2->mgso4
Mg(OH)2=MgO+H2O
MgO+2HCL=MgCL2+H2O
MgCL2+2NaOH=Mg(OH)2+2NaCL
Mg(OH)2+H2SO4=MgSO4+2H2O