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 – 72.90g
Magnesium Oxide – 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
mO = 0.06g
mMgO = 0.18g
% Mg = mMg/ mMgO x 100%
% Mg = 66.6%
% O = mO/ mMgO x 100%
% O = 33.3 %
The percentage composition by mass of magnesium oxide is 66.6% of Magnesium, and 33.3% of Oxygen.
b) One of the evidences that a chemical reaction took place is the formation of a new substance.
c) Refer to the Observations
d) Refer to the Observations
e) Refer to the Observations. This result might have been slightly different than it should be due to problems measuring the mass of the crucible and magnesium, or some of the final product escaping from the crucible.
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...