3. Place the crucible (with the lid on) on a pipe clay triangle supported on a tripod. Heat the crucible with a strong Bunsen burner flame.
4. Lift the lid carefully with tongs every 10 seconds to let the air enter the crucible. Keep heating the crucible until the reaction is complete. Remember to note any changes occurring during the reaction and the appearance of the contents of the crucible at the end of the experiment.
5. Let the crucible cool down, then find the total mass of the contents, crucible, and the lid.
6. Use the results to calculate the number of moles of magnesium and oxygen in magnesium oxide.
Results
Mass measured before the experiment
Crucible and lid: 53.08g
Crucible, lid & magnesium: 53.17g
Magnesium: 53.17g- 53.08g = 53.09g
Appearance of magnesium
Before experiment: Shiny grey/ silver, ductile/ malleable
During experiment (in order): Turns bright orange, releases white smoke, magnesium glows, turns into powder, powder becomes white.
After the experiment: white, powdery, brittle, still in shape of coiled magnesium.
Mass measures after the experiment
Crucible & magnesium oxide: 53.25g
Magnesium oxide: 53.24g- 53.08g= 53.16g
Oxygen: 53.16g- 53.09g= 53.07g
Mg O
Mass 0.09g : 0.07g
Ratio 1g : 1.2g
1g : 1g ∴MgO
Conclusion
The result of this experiment shows that the formula of magnesium oxide is MgO. This means that one mole of magnesium should combine with one mole of oxygen in order to form magnesium oxide.
This experiment of making magnesium oxide using magnesium as a raw material is an example of an exothermic reaction. Different issues can affect the results. E.g. the amount of oxygen reacting with the magnesium can be affected by the number of times you lift the lid during the reaction; the amount of time the reaction takes to complete can be affected by the strength of the Bunsen flame. Also, the magnesium ribbon we used might not be pure magnesium and therefore the magnesium oxide we made from the experiment may contain other materials, which will affect the accuracy of the mass of magnesium and oxygen.
To improve the quality of the experiment, it’s important to use pure magnesium to make sure that the substance we make only contains the two materials we need, which is oxygen and magnesium. You should also let in reasonable amount of air into the crucible during the experiment to complete the reaction that will provide possibly the most accurate results.