Magnesium Oxide Lab

Purpose: The purpose of this lab is to experimentally determine the empirical formula of magnesium oxide. To do this, we will measure the weight of the magnesium before the reaction, then we will measure it after it has bonded with the oxygen. We will then imply formulae to determine the imperical formula of magnesium oxide. My hypothesis is that the formula will be Mg₃O₂, because the oxygen has three unfilled electron pairs, and the Mg has two.

Data and Calculations:

Object	Mass
Empty Crucible and lid	21.97
Empty Crucible and lid and Magnesium	22.35
Empty Crucible and lid and combustion product	22.57
Magnesium net weight	21.97-22.35=0.38
Combustion product net weight	22.57-21.97=0.6
Weight of oxygen in product	0.6-0.38=0.22

Analysis:

1) The mass of the Mg used is .38 g

2) The number of moles used is .38/24.30 = 0.016

3) Mass of magnesium oxide formed: 0.6 g

4) Mass of O combined with Mg: 0.22 g

5) Number of moles of O: .22/16 = 0.014

6) Ratio between Mg and O: 0.014/0.016 = 14/16 = 7/8

7) Empirical Formula: O₇Mg₈

8) No accepted value provided by teacher. Therefore, answer not applicable.]

9) Majour sources of error include: Loss of matter via particle dispersion via atmosphere. This would make the product lighter than it is supposed to be, and have less Mg than it is supposed to have. Not waiting long enough to cool the crucible would cause different values in the mass. This makes the experiment inaccurate.

10) N/A I have not conferred with other members in the class.

11) In a molecule of C₂H₆, there would be 2 atoms of Carbon, and 6 atoms of hydrogen. In a mole of the same substance, there would be 24g of carbon, and 6 grams of hydrogen.

Results/Discussion: I have discovered from all this data, that the empirical formula for magnesium oxide is O₇Mg₈, contrary to my hypothesis, which I know must be true – Mg₃ O₂. I make this conclusion, because I have been taught that when ions bond, they do so in direct relevance to their valence electrons. Since Mg has 2 valence electrons, and O has 3 open spaces, then if you have 2 oxygens, you have 6 open spaces, and if you have 3 magnesiums, you have 6 valence electrons. Then they fit together like a hand and a glove. Therefore, I must have made some frightful error in my experiment. See analysis question 9 for more information.