Question

1. Based on the Data Table, what mass of magnesium is contained in your compound? Show all calculations.

31.634 – 31.064 = 0.57


2. Based on the Data Table, what mass of oxygen is contained in your compound? Show all calculations.


3. Compare the mass of the Mg ribbon with the mass of the magnesium oxide. How can you account for the change in mass between the two?


4. Now that you have the mass of magnesium and oxygen in your compound, you can find moles of each element in the compound and you can determine your experimental empirical formula. Show all calculations and your empirical formula below.




5. What is the known formula for magnesium oxide? Compare the known formula to the empirical formula you determined in question 4. Are they the same or no?

Answer 1

Answer:
Answer 1: The mass of magnesium contained in the compound is 0.57g, which can be determined by subtracting the mass of the crucible and lid (31.064g) from the mass of the crucible, lid, and magnesium ribbon (31.634g).

Answer 2: The mass of oxygen contained in the compound is 1.39g, which can be determined by subtracting the mass of the crucible, lid, and magnesium oxide (31.970g) from the mass of the crucible and lid (31.064g).

Answer 3: The change in mass between the two can be accounted for by the reaction of the magnesium with oxygen to form magnesium oxide.

Answer 4: The number of moles of magnesium is 0.0995 (2.39/24) and the number of moles of oxygen is 0.0868 (1.39/16). Dividing the moles of each element by the smallest amount of moles (0.0868) results in a simplest ratio of 1:1. Therefore, the empirical formula of magnesium oxide is MgO.

Answer 5: The known formula for magnesium oxide is MgO, which is the same as the empirical formula determined in question 4.