What is the mass of crucible and lid?
Results
| Step | Mass (g) |
|---|---|
| Mass of crucible and lid (step 1) | 50.00 |
| Mass of crucible, lid and magnesium (step 3) | 50.24 |
| Mass of crucible, lid and magnesium oxide (step 7) | 50.40 |
Why is the lid lifted from time to time during heating?
Carefully lift the lid from time to time to allow sufficient air into the crucible for the magnesium to fully oxidise without letting any magnesium oxide escape.
Why are the empty crucible and cover fired?
The empty crucible and cover are fired to red heat in order to burn off impurities in the crucible and to establish a constant weight.
How much does a crucible and cover weigh?
The crucible and cover weighs 14.300 grams.
What does magnesium ribbon do?
The burning magnesium ribbon produces light of sufficient intensity to cause temporary loss of sight. Avoid looking directly at the light source. The burning of magnesium in air produces intense heat which can cause burns and initiate combustion in flammable materials.
Why must the crucible lid be opened once?
Lid of the crucible must be opened once in a while during the heating process of magnesium. To let it the oxygen gas to ensure there is sufficient/enough oxygen gas for complete reaction. To ensure all magnesium as fully reacted with oxygen to form oxygen oxide.
Why should you leave the crucible cover ajar while heating?
While heating the crucible, you must have the lid partially ajar to allow water to escape. You will want a gentle blue flame. Orange flame produces carbon soot which will coat your crucible and alter the weight.
Is it OK to handle the crucible with your hands?
Do not touch the crucible with your hands (oils contaminate it and/or you could be severely burned). Do not place a hot crucible on a lab bench (the temperature difference may cause it to break). Use the clay triangle.
Why do we heat the crucible before weighing it?
You must let the crucible cool before measuring it because the heat from the crucible warms the surrounding air, which rises, then that air cools down and falls. This rise and fall of surrounding air is called a convection current and will give you an unsteady reading that is rising and falling.
Why must the lid of the crucible be off while heating?
