# Empirical Formula of Magnesium Oxide

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Empirical Formula of Magnesium Oxide Date: Aim: The aim of this experiment was to determine the empirical formula of magnesium oxide. Equipment: · Balance · Crucible and lid · Bunsen burner · Magnesium ribbon (0.2g) · Steel wool · Crucible tongs · Pipe clay triangle · Tripod Procedure: 1. Obtain a clean, dry crucible and lid, then heat them for approximately 5 minutes over a Bunsen burner 2. Clean the surface of a 20 cm strip of magnesium ribbon using steel wool 3. Coil the magnesium ribbon, so that it fits into the crucible 4. Weigh crucible and lid on a balance, and record the mass 5. Place magnesium ribbon into crucible, replace the lid and weigh once more 6. Heat the crucible and its content with the lid off until the magnesium begins to glow 7. Replace the lid and heat the crucible strongly 8. Continue to heat the crucible, occasionally lifting the lid with tongs to provide oxygen for the reaction 9. When all magnesium has reacted, remove the lid and heat strongly for 5 minutes 10. Replace crucible lid and allow to cool 11. Reweigh the crucible with its contents and lid Observations: Once the magnesium was in the crucible and was being heated by the Bunsen burner, it glowed for a brief time. It then caught fire before the lid was placed on top. When it came into contact with the oxygen, the magnesium started glowing extremely bright, and intensely white. The glow became orange after some time. The magnesium ribbon then turned white. Results: Mass of crucible and lid 29.9 g Mass of crucible, lid and magnesium 30.1 g Mass of magnesium 0.2 g Mass of crucible, lid and magnesium oxide 30.3 g Mass of magnesium oxide 0.4 g Mass of oxygen combined with magnesium 0.2 g Questions: 1. a) The mass of magnesium which reacted was 0.2 grams. b) The mass of oxygen that combined with the magnesium was 0.2 g. 2. What is the empirical formula of magnesium oxide? Mg0.2 g0.224.310.0080.0081=2 O0.2 g0.2160.01250.0081.56 =3 Thus the empirical formula of Magnesium Oxide is Mg O . 3. Why are the crucible and lid heated at the beginning of the experiment before being weighed? The crucible and lid are heated at the beginning of the experiment before being weighed so that any moisture in the crucible is burned away. Moisture is heavy, and thus it can change the results of the experiment, as we only want the weight of magnesium and the magnesium oxide. 4. What are the possible sources of error in this experiment? Possible sources of error in this experiment include the inaccuracy of measurements, as correct measurements are vital for the experiment. The loss of magnesium oxide smoke can also be counted as a possible source of error: if you should lose some of the smoke, there would be a less amount of magnesium oxide than expected at the end of the experiment.