Sciencemadness Discussion Board

Hopelessly gunked up reaction vessels

madscientist - 25-9-2002 at 09:02

I recently tried to prepare CS2 from charcoal and sulfur, and for whatever reason I'm not able to condense what's being produced by heating the mix. I don't want to go through several gas canisters trying to bake out 150g of sulfur and 25g of charcoal out of this flask. I don't think that acetone is going to loosen this hunk much, if at all. Trying to burn it by jetting in oxygen gas and igniting would obviously be dangerous, and risking the destruction of the flask. I don't want to spend all afternoon carefully chiselling away with a metal rod either. If anyone is struck with a great idea for cleaning out the mess, please share...

An idea

Polverone - 25-9-2002 at 10:02

I think you need to attack the sulfur. Hot concentrated alkali solutions should do this. So should a heated solution of nitric acid (just add H2SO4 and a nitrate and apply heat).

150 g is a pretty hefty hunk of sulfur, though. Does it not flow at all when heated? It would be better if you could remove the bulk of the mass just by heating and pouring it out, then clean the glass with chemicals. Otherwise you may need quite a lot of chemicals.

rikkitikkitavi - 25-9-2002 at 11:09

CS2 is made by leading S-vapour over charcoal (or similar porous carbanceous material) at 800 C.

Autoignitionpoint in air is 90C! So boiling water would ignite it!

As for the cleaning: I would try to do as
vulture says. Oxidizing the S or C would take lots of precious powerful oxidants(not to mentioning the risks), simpler to react the S with OH- into S2-.
Or even more simply trying to melt it out.

/rickard

rikkitikkitavi - 25-9-2002 at 11:11

/me sorry.

I meant Polverone.

Damn this non-edit-function. Now everyone can see that I am such a confused person.

/rickard

PHILOU Zrealone - 25-2-2003 at 10:31

I have also played with C activ carbon dust (black of lamp kind) and S to try to make CS2!
I not only discovered it doesn't make CS2, but it makes a brittle solid that can melt and have a metallic shine when hardened on a smooth surface (dark grey mirror)!
I have used it a while to close my first pipe bombs.I really look glass when it is cold.
It corrodes metals (I was using inox tool to melt it).It is flamable and burns blue (S); once burning it stick to every surface providing black liquid droplets that are in fire and set fire!

Thus first melt as much as possible to flow maximum out as a liquid; remelt the inner walls and do it a second time!
Avoid NaOH since it corrodes glass and Al metallic alloys!

Then try to chisel it gently; if the surface is glass it will come by big pieces, if it was metal then it might be a bit harder but you don't have to be as cautious!
Melt a little wet NH4NO3 to get rid of the remaining solid and burn!The oxydative power of NH4NO3 will form SO2 and CO2!

PH Z