# 5 F2F - Percent Composition - MgO.docx - Name Percent...

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Name: Percent Composition – Synthesis of Magnesium Oxide Supplies : Stainless Steel Crucible with lid, Ring stand with ring clamp and clay triangle, Bunsen or Meker burner, crucible tongs, Magnesium turnings, High-purity water (HPW) Summary : A chemical formula represents the ratio of atoms in a substance. You will convert magnesium to magnesium oxide and prove that the ratio of the weights of magnesium and oxygen are the same as those predicted by the periodic table. Equations : % massOxygen = Mass O Mass MgO 100 Percent error = | truevalue experimental | truevalue 100 Safety considerations : Do not ever pour water on burning magnesium metal if it gets out of control—it may explode. If there is an uncontained fire involving magnesium, quench it by covering it with sand . You are going to cause a reaction between magnesium metal and oxygen gas to form magnesium oxide. Write the chemical equation for this overall reaction in the space below : 1. Clean your crucible and lid with water (and soap if necessary), then place it in the clay triangle and strongly heat it over a burner for 2-3 minutes. This is to ensure that it is both clean and dry before weighing. Weigh the cooled crucible without lid , add to it approximately 0.500 g of the magnesium metal and reweigh.