Mg(s, silvery-white) + O2(g)
limiting reagent
MgxOy(s, white)
0.353 g of Mg solid
Atmospheric oxygen in excess
heat
Result:  Mass of MgxOy = 0.585 g
Determining the Empirical Formula of Magnesium Oxide

The goal is to determine x and y in the unknown magnesium oxide, MgxOy, by burning a known
mass of Mg in an excess of oxygen.