Sciencemadness Discussion Board

Ammonium Dichromate Volcano

lvjrf - 14-10-2004 at 03:55

Ammonium dichromate (NH4)2Cr2O7

when decompoed Ammonium dichromate (the reaction like volcano)
we obtain Cr2O3 + N2 + H2O
the Cr2O3 Used as catayste

I want to ask
how can we prepare Ammonium dichromate (NH4)2Cr2O7 ??

Edit: Changed title.

[Edited on 16-10-2004 by chemoleo]

guy - 14-10-2004 at 20:47

http://www.rhodium.ws/chemistry/potassium.dichromate.html

This is rhodiums site for making Potassium dichromate. But instead of using potassium chloride, you could use NH4Cl to precipitate the NaCl and ge ammonium dichromate.

Tacho - 15-10-2004 at 09:52

I strongly advise you to check the MSDS of these chromium salts before you mess around with them. Some are linked to cancer.

The smoke of your volcano is something I would like to stay away from.

[Edited on 15-10-2004 by Tacho]

vulture - 15-10-2004 at 10:06

The "smoke" consists of water, nitrogen and chromiumtrioxide, which are harmless.

Only chromium 6+ compounds are carcinogenic.

chemoleo - 15-10-2004 at 12:15

??? Chromiumtrioxide, CrO3, is VERY toxic, and VI+! Besides that would be oxidised... so knowing my old friend vulture I presume you meant Cr2O3, which normally (or so I think) comes under the name chrome oxide?
This oxide is green, and indeed not very toxic. When I did the ammoniumdichromate volcano recnetly, it'd leave a fine Cr2o3 residue - which could be used straight for a thermite reaction with Al :D. I think I may have mentioned that in the exotic thermites thread.
Anyway - lvrf, I think the making of dichromates has been covered in a thread here (apart from the rhodium procedure), search and you shall find. Then you could make the ammoniumform from it as guy suggested.

Cr2O3

MadHatter - 16-10-2004 at 20:18

Makes a spectacular thermite mixed with powdered Mg. Use some welding goggles
when watching this one !

Thanks for all

lvjrf - 17-10-2004 at 03:18

Thanks for all

I am a fish - 17-10-2004 at 04:01

When I've done the volcano experiment, small amounts of unreacted (NH4)2Cr2O7 have always remained. Crystals of it get scattered away from the main pile without being ignited, and consequently don't react.