Title: Determining an Empirical Formula Objective: Using mass relationships, show that magnesium and oxygen combine in a definite whole number ratio by mass. Equipment: Materials: 35 cm of magnesium ribbon Procedure: Data: Mass of empty crucible ________g Mass of crucible + Mg _________g Mass of crucible + O __________g Calculations: 1. Find the mass of Mg 2. Find the mass Of O 3. 4. 5. Find the number of moles of Mg Find the number of moles of O Find the whole number ratio Conclusions and Questions: 1. Write the empirical formula for magnesium oxide. 2. What was the ratio by mass of Mg used to the mass of O used? How does it compare to the mole ratio? 3. The molecular mass of a compound is 75 grams and the empirical formula is CH3. Calculate the molecular formula. 4. How is the chemical composition of carbon monoxide similar to that of carbon dioxide? How is it different? 5. A sample of sulfur having a mass of 1.28 g combines with oxygen to forma compound with a mass of 3.20 g. What is the empirical formula of the compound?