Magnesium burning in dry ice (high quality video)

HD (click "high quality") annotated video of magnesium shavings burning inside a block of dry ice. Amazing sight.
Note: The Mg seems to burn *better* in CO2 than air, though CO2 is an inferior oxidizer to O2. I speculate it is because air is 20% O2 versuss 100% CO2 within the dry ice. Mg in pure O2 would be potentially explosive (definitely so if powdered).

Category:

Science & Technology

Tags:

• carbon
• dry
• burn
• burning
• dioxide
• ice
• magnesium
• science

[LordiRockz]

Can somebody explain it to me, why is it that only magnesium burns in CO2?

[doug123yt]

@LordiRockz : Good Q. Other things, especially flammable metals like sodium, will burn in CO2. Magnesium just happens to be a relatively safe and convenient choice for demonstration.

[Fordi]

Will thermite burn in CO2?

[doug123yt]

@Fordi : Thermite has its own oxidizer mixed in -- the iron oxide. It requires no atmosphere at all to burn, and is in fact very difficult to extinguish.

[doug123yt]

I'm bummed by the pseudo-expert posts proposing bigger and better fires or explosions. It doesn't take much thought to set a pile of something on fire. The point here is to illustrate chemistry with a clear annotated video of a beautiful and simple (but not risk-free) reaction. Video your explosions and post them yourselves; try not to lose too many fingers along the way.

[JimNoir1]

@pixelpatter01 Ah, well thats what I've read thats all. Thanks for telling me that.

[pixelpatter01]

@JimNoir1 Covering burning Mg with sand won't put it out. The Mg will react with the sand to make MgO and Magnesium Silicide. The Mg2Si will then react with water or other acids to produce Silane gas, a dangerous pyrophoric and poisonous gas. DRY NaCl salt is the only common material that would have a chance to put it out. Moist sand will be even worse. Best is to remove the non burning magnesium and wait. BTW severe UV hazard to look at.

[JimNoir1]

@LordiRockz Ha! I just did a chemistry lesson on it!

2 Mg(s) + CO2 >2 MgO(s) + C(s)

Magnesium + Carbon Dioxide reacts to form Magnesium Oxide and Carbon Allotropes.

This is why Carbon Dioxide cannot be used to extinguish Magnesium fires. And nither can water.

Being a highly reactive alkali metal the best way to extinguish a Magnesium fire is to cover it with sand.

Calcium is even worse...

[Luckyjasondrum]

Nice.  End result is very interesting. Great coloration!!!