What percentage mass of magnesium oxide is magnesium?

Determining the Empirical formula of Magnesium Oxide?

• how would i get the percentage composition & empirical formula of the magnesium oxide? this is the info i have : ------------------------------- - Measured Mass (g) Dry Crucible and lid ---------------------15.22 g Crucible, lid and Mg ribbon -----------1 5.26 g Cooled, crucible, lid and contents-- -15.27 g used 0.04 grams of magnesium in the reaction 0.05 grams of magnesium oxide was produced thanks in advance

• Answer:

  It doesn't look like your data is really accurate enough to get this right. If it is more important to know how to analyze the data than it is to have the correct data, here is the way to analyze the data. Mass of Mg = 0.04 g Mass of Mg oxide = 0.05 The difference between these two values (0.01 g) is the mass of oxygen that is present in Mg oxide. Then take the mass of Mg and O and convert to moles using molar mass from the periodic table. 0.04 g Mg/24.305 g/mol = 0.0016 mol Mg 0.01 g O/15.9994 g/mol = 0.00063 mol O Take the ratio of these two to find the ratio of Mg to O in the compound. Divide by the smaller of the two numbers: Mg 2.5 O 1.0 You want a whole number ratio, so multiply each value by an whole number so that both numbers become whole numbers, or at least pretty close. If you multiply both numbers by 2 you get: Mg 5 O 2 This would make the formula of magnesium oxide Mg5O2 from your data. The actual formula is MgO, however, so you need a more accurate balance to get better data.