Sciencemadness Discussion Board - KClO3 heated to make KClO4

KClO3 heated to make KClO4

metalresearcher - 20-8-2013 at 11:46

In an old chemistry textbook "Laboratory methods of Inorganic Chemistry by Biltz" (1928) I found this (1st picture) so I tried it out.
Not 50g but 10g of KClO3 heated in a porcelain crucible just to melt (I checked the temperature with an infrared thermometer and kept it around 400ºC) and let it cool down.
No bubbles of oxygen appeared so there was virtually no decomposition to KCl.

Tomorrow I'll add 10ml of cold water to extract KCl and see whether really KClO4 forms.

[Edited on 2013-8-20 by metalresearcher]

Varmint - 20-8-2013 at 13:34

Do a search for: AD003174

It is a now unclassified US Govt document on the process and the real-world findings.

DAS

AJKOER - 22-8-2013 at 14:01

Here is a related (untried) path based on Chloric acid HClO3. Per Wikipedia (http://en.wikipedia.org/wiki/Chloric_acid ), to quote:

"It [Chloric acid] is stable in cold aqueous solution up to a concentration of approximately 30%, and solution of up to 40% can be prepared by careful evaporation under reduced pressure. Above these concentrations, and on warming, chloric acid solutions decompose to give a variety of products, for example:

8HClO3 → 4HClO4 + 2H2O + 2Cl2 + 3 O2
3HClO3 → HClO4 + H2O + 2 ClO2

The decomposition is controlled by kinetic factors: indeed, chloric acid is never thermodynamically stable with respect to disproportionation...Chloric acid is a dangerously powerful oxidizing agent and will cause most organics and flammables to deflagrate on contact. "

Now, a problem that has been experienced using Oxalic acid to prepare acids (see thread http://www.sciencemadness.org/talk/viewthread.php?tid=18963&... ), is that it does create, at times, a highly concentrated version of the acid that is capable of further oxidizing excess H2C2O4 itself to gases (dangerously so at times). However, per the above comments per Wikipedia, targeting a concentration of HClO3 of 40% should be doable. On warming, Perchloric acid is formed and adding K2CO3 forms KClO4, H2O and CO2.
----------------------------------------------------------------------------------------------------------------------

Another path (also untried) is via Chlorine perchlorate which is prepared by the photolysis of ClO2 at room temperature and reacting the Chlorine perchlorate with KCl to form KClO4 (see discussion at Wikipedia under Chlorine perchlorate).

[Edited on 22-8-2013 by AJKOER]

kristofvagyok - 22-8-2013 at 14:37

Quote: Originally posted by metalresearcher

In an old chemistry textbook "Laboratory methods of Inorganic Chemistry by Biltz" (1928) I found this (1st picture) so I tried it out.

It works, it is a good old recipe, there is just only a little problem with it: if traces of oxidizable organics is somehow left in the crucible or in the KClO3, than it could easily explode. Not joke.

Pyro - 22-8-2013 at 14:42

Ive had something similar to that.
I had ground S and a few days later I ground KClO3 in it and could hear little pops

Pulverulescent - 23-8-2013 at 01:08

Quote: Originally posted by Pyro

Ive had something similar to that.
I had ground S and a few days later I ground KClO3 in it and could hear little pops

I fail to see the similarity, can you enlighten us?

AndersHoveland - 23-8-2013 at 07:16

I also want to point out here that it is important that the chlorate being heated is free from transition metal impurities. If the chlorate contains any manganese salts, for example, it will have a strong catalytic effect and heating will result in decomposition of the chlorate to oxygen before any perchlorate can form.

And to get rid of the remaining chlorate, just add hydrochloric acid. Hydrochloric acid will reduce the chlorate but not react with the perchlorate. The perchlorate can then be removed by fractional crystallization, either as potassium perchlorate or ammonium perchlorate, since these are much less soluble than chlorides. In contrast to the other salts formed by ammonia, ammonium perchlorate is one of the least soluble ammonia salts, almost surprisingly so.

Another variation of this reaction...
Fowler and Grant found that on heating chlorate with silver oxide that the chlorate was completely converted to perchlorate without loss of oxygen, metallic silver also forming.
J. Chem. Soc. 57, 272 (year 1890)

[Edited on 23-8-2013 by AndersHoveland]

Pulverulescent - 23-8-2013 at 08:27

Quote:

Fowler and Grant found that on heating chlorate with silver oxide that the chlorate was completely converted to perchlorate without loss of oxygen, metallic silver also forming.

Interesting! I found the reaction mentioned here!

Quote:

Oxide of Silver, " Although the mixture of silver oxide and chlorate was heated for considerably over an hour at a temperature far above that at which silver oxide decomposes (270" " 280"), no evolution of gas took place. On treating the contents of the bulb with hot water and filtering, pure silver was left behind, and the filtrate contained large quantities of potassium perchlorate.

Varmint - 23-8-2013 at 09:13

Unfortunately, the text Posted by Pulverulescent and the assertion made by AndersHoveland aren't in complete agreement.

"large quantities" and "completely converted" leaves quite a bit of room between the two. This isn't a jab at either poster of course, I'm just pointing out the deficiencies of a record that consited of generalities, not specific weights and measures.

If they had taken time to state the mols in/out, and justified directly (100% perchlorate + metallic Ag) there would be no wiggle room. As it stands, the match doesn't quite play out.

AD003174 suffers similar deficiencies, they clearly say "the stated reactions are oversimplified". Lets take a look at the section of the document where they mention:

4 NaClO3 + heat = 3 NaClO4 + NaCl.

The go on to say 2 NaCl03 + (they meant =, so much for official document proofreading) 2 NaCl + 3 O2.

Seems to me there is a lot of missing data here, and while the disclaimer "The exact mechanism of the conversion is unknown" is somewhat standard, it seems to be a pretty hefty understatement!

Ergo, even official government studies and evidenciary statements by researchers leave quite a bit to be desired when trying to nail things like this down.

The upshot is, these two sources represent unsetlled science, neither one of the offers enough in the way of hard data to guarantee repeatability by a 3rd party. This means we (those interested in the topic) can take the time to run some clean processes, and in doing so, settle the Chlorate + heat = Perchlorate issue, once and for all.

DAS

Pyro - 23-8-2013 at 09:16

even though you think something is clean, it isn't and can be very dangerous in some situations

Pulverulescent - 23-8-2013 at 11:52

Quote:

"large quantities" and "completely converted" leaves quite a bit of room between the two. This isn't a jab at either poster of course, I'm just pointing out the deficiencies of a record that consited[sic] of generalities, not specific weights and measures.

Thermal oxidation of chlorate isn't normally driven to completion either so incomplete conversion isn't a problem ─ the time required for completion of conversion is . . .

Varmint - 23-8-2013 at 16:43

Pulverulescent:

Interesting you took the time to argue for arguement's sake. If you or the other poster had mentioned speed as the focal point, then certainly your reply would have merit.

Instead, you sought to find a way to reply to make it look as though I wasn't paying attention.

Hint: Paying attention was the genesis of my original post.

Thanks,

DAS

Pulverulescent - 24-8-2013 at 02:15

Quote:

Instead, you sought to find a way to reply to make it look as though I wasn't paying attention.

What's this? I give info and you get paranoid?