oxygen in neat (no solvent) byproducts: lead oxide; reaction of MgO with PbS on heating in presence of O2 with intermediate formation of sulfide; heating to 800-900 °C in N2 atm. causes no reaction);;
oxygen in neat (no solvent) byproducts: copper oxide; reaction of MgO with Cu2S on heating in presence of O2 with intermediate formation of sulfide; (heating to 800-900 °C in N2 atm. causes no reaction);;
