Aims
When magnesium is heated in air, it reacts with oxygen. During this oxidation reaction, magnesium oxide is produced. This increases the mass. If we know the mass of magnesium at the start, and the mass of magnesium oxide produced at the end, we can work out the mass of oxygen which has been combined with the magnesium. We can use these masses to work out the formula of magnesium oxide.
Apparatus
Googles crucible and lid
Bench mat tongs
Tripod 10cm length of magnesium ribbon
Bunsen burner small piece of sandpaper
Pipe clay triangle digital balance
Safety Guidelines
1) Goggles must be worn always
2) Tie hair up or back
3) Loose or baggy clothing must be rolled up or tucked in
4) Clear the area, books chemicals etc.
5) Ensure the room has a fire extinguisher
6) Never leave the Bunsen unattended, give it your full attention
7) If equipment needs moved ensure the Bunsen is turned off or at least secured
Methods
1. Weigh the empty crucible with its lid, and write down the result in a table.
2. Clean the piece of magnesium ribbon with sandpaper and then coil it loosely around a pencil. Put the magnesium ribbon into the crucible and put the lid on. Weigh the crucible, lid, and magnesium together, and write down the result in your table.
3. Put the crucible onto the pipe-clay triangle. Leave the lid slightly ajar to to allow air into the crucible. Heat gently for a minute, then strongly. Continue heating until the reaction has finished (the magnesium will glow at first and then turn into a grey powder).
4. Turn the Bunsen burner off, and allow the crucible to cool for a few minutes.
5. Reweigh the crucible with its lid and contents, and write down the result in your table.