1. Handle the dry ice with protective gloves.
2. Remove any combustible items because some burning Mg turnings may fly out.
3. Warn students not to stare directly at burning Mg. Dark colored safety glasses can be worn which absorb most of the UV light.
Procedure:
1. Two blocks of dry ice with at least one smooth surface are needed. Using a heated deflagrating spoon, make a rough cavity about 2-3 cm deep and about 4 cm in diameter.
2. Fill the cavity with Mg turnings and place the dry ice on a protective mat.
3. Ignite the Mg tumings. Place the other dry ice block on top of the block with the burning Mg.
4. The intense light easily penetrates the dry ice. Darkening the room enhances the effect.
5. When the reaction is complete, the products can be exposed to view. The students can identify the black mass as carbon and the white powder as MgO. 2 Mg + CO2 -> 2 MgO + C Tips:
1. This shows that a carbon dioxide fire extinguisher would not be helpful with a magnesium fire.
2. This is a good demo when discussing single replacement reactions or chemical changes.
Disposal:
After cooling, the residue can be placed in solid waste container.