Hello,The formula of compound magnesium oxide can be determined if the mass of each element in the compound is known. The mass increase that results from the reaction with oxygen will give the mass of oxygen in the compound. By converting the grams of Mg and grams of O in the compound into moles, the simplest formula for the compound can be determined. Thanks a lot....Magnesium Citrate
Very nice video you have shown to determine the determine empirical formula of magnesium oxide .