I've been toying with the idea of using thermite for a demonstration again, but I only have 8 mesh aluminum. will that be fine enough or should i go and buy something finer?

I think around 500 mesh is standard fare. If you want to see molten iron, you're going to need quite a bit of the stuff. Do it outside and at a distance of course, but I shouldn't need to tell you that. Steam explosion risk on wet ground...flying molten metal and alumina if it goes badly...etc.

 

For people reading this, hermann is a chemistry professor and is well aware of the safety issues involved. There's no need to repeat them ad-nauseum for his sake.

thanks for that, UC.

 

And just for an indication of the level of risk involved... i've been considering this demonstration for a year now, and i'm only just finding the confidence to try it.

Well, if have done this experience my self. I used 400 mesh aluminum powder,bought it from ebay for 15 euros 500 grams. About the lighting method i would use the potassium permanganate/glycerin instead of magnesium ribbon.

 

Regards.

 

Carlos

I ended up just buying a premixed thermite, because it was actually cheaper than the separate components.

 

I prefer magnesium ribbon because it avoids any confusion to the students. They might imagine that the potassium permanganate and glycerin are somehow involved in the reaction. Plus of course the ribbon adds to the drama, makes it look a lot like a fuse on a bomb.

I ended up just buying a premixed thermite, because it was actually cheaper than the separate components.

 

I prefer magnesium ribbon because it avoids any confusion to the students. They might imagine that the potassium permanganate and glycerin are somehow involved in the reaction. Plus of course the ribbon adds to the drama, makes it look a lot like a fuse on a bomb.

 

KMnO4/glycerin has a predictable time delay and is more consistent though. I used sparklers as my fuses and they worked quite nicely.

magnesium is fairly predictable too, and i have tons of the stuff