Determination of Magnesium Oxide’s Empirical Formula
This procedure’s main purpose was to synthesize Magnesium Oxide through a roasting process
to determine the ratios of each element. We roasted pure Magnesium of known mass to create
Magnesium Oxide, and weighed this to measure how much oxygen was absorbed, and therefore
the ratios of each element in the resulting compound. We found that the empirical formula of
Magnesium Oxide is Mg1O1.
Joseph Proust, a highly successful French chemist of the 19th century, discovered the Law of
Definite Proportions. He found that for a given compound, the proportions of each element will
always be constant. Proportions are the defining numbers in an empirical formula. Though
molecular formulas are more complicated to derive, empirical formulas can be fairly simple to
derive through experimentation by measurement of the mass of each element in a compound. In
this experiment, we derive the empirical formula of Magnesium Oxide by synthesizing it with a
known amount of Magnesium and a measured amount of oxygen to find it’s proportions.
First, to explore the combustion of Magnesium, we burned a small strip of it. We noticed that it
burned extremely bright, too bright to observe directly. When it was finished burning, it left a
white powder residue.
We then set up our bunsen burner to roast a crucible with a small amount of Magnesium. First,
we set the flame on the empty crucible to dry out all the water contained within the ceramic.