Trial One
Mass of crucible and cover:
Mass of crucible, cover and magnesium metal:
Mass of magnesium metal:
Mass of crucible, cover and magnesium oxide:
Mass of magnesium oxide
Mass of oxygen in magnesium oxide
Percent Mg in magnesium oxide
Percent O in magnesium oxide
Mole of Mg used
Mole of O used
Ratio: mole Mg/mole O
Formula of magnesium oxide
Trial Two
Mass of crucible and cover
Mass of crucible, cover and magnesium metal
Mass of magnesium metal
Mass of crucible, cover and magnesium oxide
Mass of magnesium oxide
Mass of oxygen in magnesium oxide
Percent Mg in magnesium oxide
Percent O in magnesium oxide
Mole of Mg used
Mole of O used
Ratio: mole Mg/mole O
Formula of magnesium oxide
Calculations
% Mg in magnesium oxide
% O in magnesium oxide
Mole of Mg used
Mole of O used
Ratio: mole Mg/mole O
Discussion Questions
Surprise! The actual formula of magnesium oxide is MgO. What is the calculated value for the % by mass Mg and O, based on the atomic and formula weights?
How do your experimental values for % Mg and % O differ from the values calculated above? Determine your % error for both samples
Suggest some reasons why your experimental results differ from the values calculated for the formula MgO.
Suppose that your mass determinations for both magnesium and the magnesium oxide product were obtained only to the nearest 0.1 gram. Would your data have enabled to distinguish between such possible formulas as Mg2O, MgO, Mg2O3 or MgO2
Should the use of a different mass of Mg for the second sample make any difference in the results? Explain.
Write balanced chemical equations for the reactions Mg3N2 with water. The products are Mg(OH)2 and NH3. Write a balanced chemical equation for the thermal decomposition of Mg(OH)2 to MgO
Suppose the magnesium that you used in each sample combined only with nitrogen to form Mg3N2 exclusively. What mass of water would be required for each sample, to completely convert the Mg2N2 formed to Mg(OH)2, according to the equation in the previous question? Given the density of water is about 1.0 g/mL how many mL of water would be required? If it takes 20 drops of water to make up one mL, how many drops of water would be required for each sample?
