Question: how to calculate empirical formula of mgo?
Answer: The ratio of atoms is the same as the ratio of moles. ...  Mass of Mg = 0.297 g. Mass of magnesium oxide = mass of Mg + mass of O. 0.493 g = 0.297 g + mass of O. Mass of O = (0.493 – 0.297) g = 0.196 g. There is 1 mol of Mg for 1 mol of O .