Identifying a metal oxide

Magnetite is Fe3O4.

The lower oxygen content will cause it to burn slower, whether the particle size is microns, or half an inch! (Some day I'll have to do an anvil with thermite, I figure a good charge to get it burning good, then go to alternating aluminum plate and taconite ore for the bulk of it, plus some calcium fluoride, magnesia and silica to get the slag good and soupy.)

You'll gain a little reaction speed with the fine powder but for the most part, all you're doing is allowing smaller charges to burn. Go with cheap aluminum or magnesium filings.

You'll know cobalt when you see it. Not by appearance but by price: cobalt oxide from the pottery supply runs around $40/lb. Cobalt is not a common metal, and what little exists would rather be used in high speed steel and nickel/cobalt super alloys

Tim

CuO/Al targets @ http://ww1.webtop100.net/~62552/xmovies.webtop100.net/banner...
Even though I've never tried to hit it with a hammer, I think it pretty insensitive. You can try precipitating it from boiling Cu sulphate solution with NaOH, though Im not sure how much water it holds onto.

MnO2/Al is pretty tame compared to CuO. But then the tamest of all, for me, is brown PbO2 Both precipitated from Pb acetate with NaOCl, and extracted from new (never seen acid) batteries always burn very slowly. Even if heated (dried) in the oven for an extended period. Very frustrating, considering its supposedly one of the most violent. Yellow/red HgO & yellow(?) Bi2O3 should be nice as well (lower boiling points).

[Edited on 8-8-2005 by Axt]

You can make a test in the store with a magnet. But I wouldn't advise bringing in test tubes and flasks or anything.

You can also just call the pottery supplier. They can answer questions about their store better than we can. They have tons of chemicals, and they had better know what copper oxide is, and while you're at it, you should stock up on some other stuff they have too, especially if there's a min. order.

12AX7, I can't believe you.... in your description of the colors copper makes in glazes, you forgot (gasp) that beautifiul metallic copper color seen mostly in reduction fired raku. (usually in conjunction with iron oxide). Surely that's not what you meant by mere "red"?

NiO is green while Ni2O3 is black or sometimes dark gray. I think chemoleo could have gotten them mixed up...

It'll probably burn like a flare. The last charge of CuO/MgAl I burned produced gaseous products, so everything in the path of the gas got metallized pink, even organics

Tim

Well for the CuO that I made for use in thermite; I added solid NaOH to a concentrated solution of CuSO4 that was nearly boiling, pretty much just CuO precipitates from the heat of the solution as well as from the exotherm of the NaOH dissolving. There was still some Cu(OH)2 there so I boiled for around 5-10 min after which time all the precipitate was black with no traces of blue and settled to the bottom of the beaker rather fast. I just directly filtered it from there and washed the CuO with lots of dH2O. One batch I did I did not wash it enough so when the CuO dried there was noticeable sodium sulfate crystals on the CuO, this however did not affect the preformance of the CuO in thermite to any noticeable degree. An ethanol or methanol wash of the CuO would help remove any sodium sulfate held in there by capillary action, but I have not botherd with this, just washing well with lots of distilled water. Just air dry till dry and then 5-10 min on a hotplate to get rid of residual moisture and it is done.

Also be sure with all steps involving heating make sure to use boiling stones and constant stirring and add the NaOH slowly. If the NaOH is added too fast to a boiling CuSO4 solution the contents of the beaker have the nasty habit of jumping out at you. As is the problem with all reactions involving so much precipitate. A good way to prevent this is to keep everything just below boiling while adding the NaOH and then raise the temperature with constant fast stirring and boiling stones while boiling the CuO to rid the remaining Cu(OH)2.

EDIT...sorry for double post, I could not edit and attach a pic.

[Edited on 12-8-2005 by rogue chemist]

Here is a pic of what happens when solid NaOH is added to boiling(or possibly superheated) CuSO4 with no boiling stones and insufficient stirring.

As for why this method for CuO makes a superior thermite...I don't really know(but I do have some speculation). Chemoleo and I had discussed this a bit in the exotic thermites thread(or was it the electrolytic production of CuO thread?). Possibly roasting the CuO on too high of heat decomposes some CuO, or perhaps in aqueous solution the CuO is less dense or more porous allowing more contact with the Al powder.