Investigation for Magnesium Oxide

Hypothesis - The idea I aim to test in this experiment is the relationship between the mass of magnesium and mass of oxygen once the magnesium has been heated and reacted with the oxygen. There will be 3 variables in this experiment. The independent variable will be the mass of magnesium ribbon as different measurements will be taken and used for each trial. The dependant variable will be the mass of Magnesium Oxide, this is a measured variable as the mass of oxygen can be calculated and will enable us to determine the formula for Magnesium Oxide. The controlled variable is that the Magnesium used is possibly from the same ribbon and after being cut into lengths was stored in the same way in plastic containers.
Preliminary - I originally did a preliminary test with Iron wool where we used a similar method but
Test the iron wool was held over the flame by tongs and not contained within a crucible. We learnt from this experiment the importance of the crucible to contain all of the metal for an accurate test because the iron wool broke off as it heated and we were left with a lot of the iron wool on the bench mats around the Bunsen burner so our calculation of the mass of iron oxide was not accurate as we had not contained all the wool and couldn’t accurately collect the pieces around that had come away, therefore no giving a true mass of Iron Oxide.

Prediction - I predict that when the magnesium and the Oxygen combine and react together the magnesium will oxidise and become heavier. I expect to see a straight line pattern from these results as I believe the more Magnesium there is the more Oxygen it will take on to form the Magnesium Oxide and so believe the results should gradually get heavier and heavier as the Magnesium gets heavier and heavier. The equation for this investigation would be Mg + O2 MgO which would balance as 2Mg + O2  2MgO. This is done as the Oxygen has two molecules which would need two Magnesium molecules to balance it out. The physical