a) The percentage composition of Magnesium Oxide should be 60% of Magnesium and 40% Oxygen. According to the Law of definite proportions, the percentage composition of a compound will always be the same, no matter what is its mass.
Before starting the Lab, we measured the mass of the porcelain crucible and after, the crucible with the Magnesium
Porcelain Crucible- 72.72g
Porcelain Crucible + Magnesium- 72.84g
After the experiment was over, we finally got our results.
Magnesium Oxide + Crucible â€“ 72.90g
Magnesium Oxide â€“ 0.18g
Now we can calculate the percentage Composition by mass of Magnesium Oxide, and answer the first question of our Lab.
mMg = 0.12g
The percentage is constant, and even if the masses were different, the percentage would still be the same, or so does the law of definite proportions states.
f) Losing any mass of product lowers the final weight which shows the amount of oxygen via the increase in weight. The final weight would not increase enough & it would give the impression that the % of oxygen was lower than it should be.
And since the weight of total product would be smaller, the grams of magnesium divided by a smaller total mass produced... would give % magnesium much larger than we expected
g) The Magnesium percentage calculation would still be the same, because the ratio between Magnesium and Oxygen will always be constant. The only difference will be the magnesium oxideâ€™s final mass, because there is less magnesium to react with oxygen.
h) The white film is composed of hydroxide, so itâ€™s essential that we remove it, so that the burnet oxygen doesnâ€™t react with hydroxide instead of magnesium.
i) Nitrogen is 4x more abundant than oxygen and might react. Magnesium nitride reacts with water to form magnesium hydroxide which can be decomposed to magnesium oxide. We can just add water to the product and heat.
j) As we compared the results with other groups, we realized that they were a bit different. But we think it was mainly because of the different crucible mass between the groups, and some of the oxygen escaping from the final product in the end. But the results ranged from 60% to 65% of Magnesium and 35% to 40% of Oxygen, meaning that the law of definite proportions could be applied on this Lab.