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Combustion of Magnesium in Carbon Dioxide

Procedure

1. There are two dry ice blocks with identical cavities in them.

2. Fill one cavity about half full with magnesium filings.

3. Light the filings with the torch.

4. Cover burning magnesium with the other block, making sure the cavities line up.

5. Dim lights.

6. After the Mg stops burning, drop the residue out and break it open.

7. The class usually wants an instant replay

Reactions

2Mg + CO₂ --> 2MgO + C

Standard heat of reaction is -809kJ.

The black residue is a mixture of carbon and magnesium nitride, Mg₃N₂.