Mass of crucible + lid + magnesium before heating =30.69g
Mass of crucible + lid + magnesium oxide after heating =30.81g
The Mass of Each element in the compound
Magnesium
Mass of crucible + lid + magnesium oxide after heating =30.81g
Mass of crucible + lid =30.41g
Therefore, the mass of magnesium =0.4g
Oxygen
Mass of crucible + lid + magnesium oxide after heating =30.81g
Mass of crucible + lid + magnesium before heating =30.69
Therefore, the mass of oxygen in magnesium oxide =0.12g
Change the masses into moles
Magnesium Oxygen
0.4 0.12
24 16
=0.0166 mole =0.0075 mole
The ratio of moles of each element
Mg : O
0.0166 : 0.0075
2 : 1
Therefore, the formula of magnesium oxide is Mg²O.
Conclusion:
Before doing the actual experiment I decided to do some preliminary work. These were to tell me the details that I would need to know for my investigation to be successful.
The Formula is Mg²O according to my result. It was not as ideal as the one shown in the book because I might have done some processes wrong. I presume that mistakes happened when I lifted the lid up frequently to let oxygen in. The distance that I lifted it maybe more than I was supposed to; in other words, I had a high possibility of lifting the lid away from the crucible longer, which meant that there was more time for magnesium oxide to escape from the crucible.
I would ameliorate the experiment next time with counting the appropriate timing and measuring the distance of lifting the lid, in order to keep the experiment fair and to the accurate figure.
By Heidi Chow 10Y