Sciencemadness Discussion Board

Interesting reactions (KCl melt) / Salt Fusions

12AX7 - 7-1-2007 at 15:05

Didn't take any pictures, but I would like to relate this interesting observation.

I melted some KCl (ground, with rust, dust, sand, asshairs and whatever other impurities float around the basement) in a steel crucible which was caked with ZnO, FeO, Cr2O3, etc. And for the hell of it, I put in some chunks of hardwood charcoal (white oak, my own product; pictures of manufacture on my website). I heated it to orange hot in a pure air atmosphere and observed sparks from the charcoal on occasion.

I suppose if it were K2O (or Na2O, or OH, or CO3), I could be seeing alkali vapors burning, but that doesn't seem likely given the chlorideness of the salt. I don't think ZnO (or any other oxide for that matter, let alone the thermally stable ones) is soluble in a chloride melt. It was hot enough for zinc to vaporize, which given the presumably reducing environment is at least possible. THat would be blue though, not sparks. I suppose it could always just be naughy charcoal throwing sparks, but I've never seen sparks like this.

*Shrug*

Say, as long as I'm on this idea, anybody have ideas for high temperature fusions? I've already done sodium manganate... I tried sodium chromate the other day, but I think I ended up with a lot of 1. nothing reacting (there were globs of ceramic grade Cr2O3 left), 2. sodium chromite (dissolving it, I got a lot of green solution?!) and 3., zinc [di]chromate, among others (evidenced by the somewhat more refractory orange spots that were left). But the thing is, even zinc chromate melts at a reachable temperature (although come to think of it, I may not have been that hot).

Tim

Theoretic - 26-1-2007 at 04:10

"(although come to think of it, I may not have been that hot)."
:o Anything to do with the asshairs?
KAlCl4, KFeCl4, K2CuCl4 and the like should be interesting.
Urea + KCl should give NH4Cl + KCNO.

[Edited on 26-1-2007 by Theoretic]

12AX7 - 26-1-2007 at 08:19

Not sure about chlorides, don't you need enclosed apparatus to contain the chlorine and anhydrousness for Al and Fe trichlorides?

What's the hazard on (and use of) cyanate? I'm not sure you'd get a reaction, urea evaporates pretty well a whole long while before KCl melts.

Tim

DeAdFX - 26-1-2007 at 21:24

Quote:
Originally posted by 12AX7
Not sure about chlorides, don't you need enclosed apparatus to contain the chlorine and anhydrousness for Al and Fe trichlorides?

What's the hazard on (and use of) cyanate? I'm not sure you'd get a reaction, urea evaporates pretty well a whole long while before KCl melts.

Tim


I hear cyanates are a lot less toxic. I believe wikipedia says that they are 7x less toxic. Curious... If the potassium chloride is slightly soluble in the molten urea then the reaction should procceed right? Hmm.. I am curious as if this works cause potassium chloride is a heck of a lot suspicious to buy in bulk(in comparison to HCl). If it doesn't work in the molten phase I assume it might work as aqueous solutions?

Theoretic - 29-1-2007 at 08:14

You don't need to contain the chlorine, there is none - there may be AlCl3 vapour in unpleasant quantity (however probably not after KAlCl4 is formed, this has LOTS of salt eutectics information) however. Anhydrousness you do need, the chlorides like to hydrolyse even with water vapour.
The urea process works (I assume it does, I don't know for sure and am conjecturing) because urea when heated isomerizes into ammonium cyanate, this would otherwise decompose to NH3 and HOCN and evaporate, however the presence of Cl- means that the cyanate ion doesn't have to protonate to form the (less volatile than HCl, even less volatile - decomposes at 320-350°C - the trimer, cyanuric acid) cyanic acid, and NH4+ protonates Cl- to sublime as NH3 + HCl. This can still happen in molten urea, but not in solution (temperature too low). If urea is thrown into molten KCl, the NH3 + HOCN vapour will probably react as it passes through the melt. Cyanates are used as alternatives to phosgene in chemical syntheses, steel-hardening agents, C reduction given cyanides, reaction with chlorosulfuric acid/sulfuryl chloride/thionyl chloride/aluminium chloride will probably give cyanogen chloride.

12AX7 - 29-3-2007 at 08:55

Bump!

Cooked up some sodium chromate last night.

Tim

12AX7 - 6-4-2007 at 23:05

Tried the urea + KCl reaction. Not knowing what to expect, I gave it hell, and it returned about a 10x multiplication in volume and copious ammonia fumes. Some of the product turned out resinous. Some of the KCl may've dissolved, but chunks were left in the bottom.

I don't have any idea how to test for cyanate. I didn't get any colored results by testing it as a ligand with Fe(3+), Cr(3+) or Cu(2+).

I also tried (in a seperate crucible) the fusion of NaOH with mixed lead oxide (it's a somewhat caked pinkish brownish powder, something like the color of a pink pencil eraser but powdery-er), with optional KClO3 oxidizer. A suprising amount of Fe(OH)3 or FeOOH was formed while the NaOH (some moist, impure stuff) cooked down. Little change was seen with the lead oxide addition.

Ya know what else, I should get a thermocouple and set up an error amplifier so I can set this thing for constant temperature. That would be perfect to electrolyse some NaOH and get a few grams of Na metal.

Tim

UnintentionalChaos - 6-4-2007 at 23:50

Concerning that last reaction, (and this is just going off wikipedia)...urea decomposes before melting to give biuret and ejects ammonia. Biuret will melt, but eventually decomposes outgassing even more ammonia and converting into cyanuric acid. When you heat that enough, you get fumes of toxic cyanic acid and probably some nitrogen oxides. Cyanic acid can polymerize with cyanuric acid forming cyamelide (probably your resinous material).

Test for cyanate? I don't know any direct test offhand, but you could reduce to cyanide which is much easier to test for.

[Edited on 4-7-07 by UnintentionalChaos]

12AX7 - 7-4-2007 at 10:56

What's a good enough reducing agent, Fe(0) + HCl? Zn? Al? Mg?

Ehh...HCl...don't like the idea of that around cyanide/ate. Maybe Al or Zn and OH-?

Tim

Dr. Beaker - 7-4-2007 at 12:07

At high temp. ("entropy driven rxns") carbon is an efficient reducing agent. So- you may have reduction of silica or iron oxides to iron and/or Si/SiC and they recombine with O2 in the form of "sparks". If this true u also make CO...(Asphyxia :o)

[Edited on 7-4-2007 by Dr. Beaker]

12AX7 - 7-4-2007 at 23:46

Say, what of urea, carbon and potash or iron (oxide, filings, ?)? Carbon and a source of nitrogen, together, tend to make cyano groups under such circumstances don't they? I'd be afraid of going after KCN or even KOCN, but I understand Fe(CN)6's are quite solid and have interesting colors.

Tim